The first issues used the standard reverse of GENIO POPULI ROMANI that had been introduced on the large folles of Diocletian's reform. The use of the dative (Genio) shows the inscription to be dedicatory and means "To the guardian spirit of the people of Rome". The standing figure represents this Genius, and holds a cornucopiae, from which all riches flow, and a patera, a small circular dish used in making sacrifices. Like the two nearest mints in Gaul (Trier and Lyons), this reverse was retained well into the Third Tetrarchy, whereas the other western mints in Italy changed to using only SACRA MONET AVGG ET CAESS NOSTR ¹ around AD 300. The forms AVGG and CAESS represent the plurals of Augustus and Caesar, implying the two emperors, (Diocletian and Maximian) and the two Caesars (Constantius and Galerius)

The inscription PROVIDENTIA DEORVM QVIES AVGG celebrating the abdication of Diocletian and Maximian can be translated as "The restful peace of the Emperors by the providence of the gods" and depicts Providence extending her hand to Quies. The obverse inscriptions on these coins are also dedicatory, D N DIOCLETIANO (or MAXIMIANO) BAEATISSIMO SEN AVG ²- "to our lord Diocletian(or Maximian) the most happy senior emperor". In the following issues this type was simplified to QVIES AVGG (and therefore just showing Quies) and confined to Diocletian, as by then Maximian had come out of his enforced retirement and made an alliance with Constantine. Although Maximian was then restored to using the normal reverse type of the emperors, now abbreviated to GENIO POP ROM, the obverse inscriptions of the coins in his name continue to use the dedicatory D N MAXIMIANO P F S AVG ("To our lord Maximian the dutiful faithful senior emperor".

Constantine's alliance with Maximian in AD 307, which seemed to confirm him in power, was a signal for a rapid departure from the stereotyped coin types of the early period. The GENIO POP ROM type continued in the names of all the rulers with some claim to legitimacy, Galerius as Augustus, Constantine and Maximinus II as Caesars and Maximian as Senior Augustus. Both Severus II, then a prisoner in Maximian's hands, and Maxentius, son of Maximian who ruled in Italy, were ignored. Diolcletian continued to be featured on the QVIES AVGG coins. Both Constantine and Maximian shared other coin types, MARS VICTOR, MARTI PATRI PROPVGNATORI and ROMAE AETER. At this time, Constantine believed he was under the protection of Mars as his tutelary god. MARTI PATRI PROPVGNATORI and ROMAE AETER are both dedicatory "To Mars the defender of our country" and "To Eternal Rome". Another type, for Constantine alone, MARTI PACIF(ero) means "To Mars the bringer of peace".

Of two other Constantinian reverses, ADVENTVS AVGG - "The advent/arrival of the Emperors" - is a normal type for the commencement of a reign and and does not necessarily imply any journey, though it might just signify Constantine's arrival in London shortly after his elevation as Caesar, since the reverse is not used elsewhere. The other type, PRINCIPI IVVENTVTIS, was a title that had long been associated with the rank of Caesar ³. Maximian was accorded one other reverse, HERCVLI CONSERVATORI, "to Hercules, the defender (of the emperor)" ⁴.

In the following year Maximian made his peace with Maxentius and returned to Italy, after first confirming Constantine as Augustus. In the immediately following period, coins were only struck in the names of Constantine as Augustus, save for one special issue for his father, Constantius, now consecrated as a god, with obverse DIVO CONSTANTIO PIO and reverse MEMORIA FELIX, showing an altar with an eagle either side. Coins in the name of all other rulers were at first completely absent ⁵. After the conference at Carnuntum called by Galerius in AD 308, Constantine had been officially downgraded to the rank of Caesar again, but this was ignored at the mint of London (as well as Trier and Lyons) where he continued to be titled Augustus. Also, following Carnuntum, Maximian was forced into retirement again and never again figured on Constantine's coinage.

Under the agreement a new emperor of the west, Licinius, replaced Severus II, who had been killed by Maximian the previous year. Maximinus II, the new Caesar in the east in AD 305, resented the promotion of Licinius over his head and after a year in which he was placated with the empty title Filius Augustorum, "son of the emperors" ⁶, declared himself emperor, circa AD 309. Shortly afterwards, Constantine resumed a coinage in the names of Licinius and Maximinus, both as Augusti. Notably, a coinage for Galerius was entirely absent.

In this coinage for himself, Licinius and Maximinus, Constantine at first confined his co-rulers to the GENIO POP ROM reverse. With his own coins there was the beginnings of a remarkable transformation. Two new reverse legends appeared, COMITI AAVVGG ("To the companion of the emperors") and SOLI INVICTO COMITI ("To Sol, the invincible companion"), both showing a standing figure of the Sun-god, Sol (who also equated to Apollo), wearing a radiate crown. Sun worship had been growing throughout the third century AD and during the reigns of Aurelian (AD 270-275) and Probus (AD 276-282) had achieved great prominence on the coinage. Constantine's conversion to the cult of Sol/Apollo stemmed, according to one of the panegyrists, to a vision he had in Gaul on his way to do battle with Maximian in AD 310. In the vision Apollo, with Victory in attendance, presented Constantine with four laurel wreaths, as a promise of successes to come. Sol thus became recognised as a protector of Constantine, who changed his allegiance from Mars and celebrated Sol on his coins, almost as an equal. His conversion to Christianity following the battle of the Milvian Bridge (AD 312) in which he eventually defeated Maxentius, at first sat easily with this devotion to Sol, and it is possible that there was some confusion in his mind with the Christian god. That this confusion was not his alone can be discerned in the fact that Sunday, the day of worship for Christians, was named after Sol and 25 December, the birthday of Sol, became the accepted date for the birth of Christ.

New reverses used after AD 312 are FELICITAS AVGG ("The happiness/prosperity of the emperors"), ROMAE AETER AVGG ("To the eternal Rome of the emperors") and ROMAE RESTIVTAE ("To the restoration of Rome"), all resulting from Constantine's victory over Maxentius and the addition of Italy to his territory.

Galerius had died a year earlier and when Maximinus II followed in AD 313, the Roman world was split between Licinius and Constantine. The coinage for Licinius continued but formed an ever-decreasing proportion of the mint's output at London. In AD 316 Constantine invaded the eastern provinces and won a series of battles, forcing Licinius back into Asia and gaining a large part of the Balkans. After that date no more coins for Licinius were struck at the London mint ⁷.

From AD 317 the coinage at London was taken up by Constantine and members of his family. His son by his first wife, Crispus, and his new-born son, Constantine Junior, by his second wife, Fausta ⁸, and less than a year old at the time of his elevation, were both made Caesar. A new reverse type appeared, CLARITAS REIPVBLICAE ("To the renown of the Republic" ⁹).

An odd coinage appeared circa AD 319, with the legend VICTORIAE LAETAE PRINC(ipi) PERP(etui) ("To the joyful and perpetual victory of the princes"). These coins anticipate the celebration of Constantine's Decennalia (tenth anniversary of his official elevation to Augustus) as shown by the shield held aloft by two Victories, inscribed VOT P R (Vota Populi Romani -"The vows of the people of Rome"). These coins, both at London and at other mints, appear to have a higher silver content or a more substantial silver wash than other issues and have been thought in the past to be a different denomination, particularly as they were hoarded separately. Possibly they were a short-lived attempt at a coinage reform. The issue also inaugurated a series of obverse busts in which the emperor or Caesars were depicted helmeted, sometimes with spear and shield, which continued until circa AD 323. The message was unmistakable, coupled in the following issue which did celebrate Constantine's Decennalia, with legend VIRTVS EXERCIT(us) ("The valour of the army") and standard inscribed VOT XX, the vows in this case being suscepta, looking forward to the completion of twenty years as emperor. The army was celebrated at that time because Constantine had just won a victory over an invading army of Alamanni.

The uneasy peace that followed was celebrated on coins with the legend BEATA TRANQVILLITAS ("The blessed tranquillity"), subsequently abbreviated to BEAT TRANQLITAS, showing an altar inscribed VOTIS XX. Above the altar is a globe, signifying that the whole world was at peace. This peace did not last for long. An invading force of Sarmatians under their king Rausimondus was defeated in the province of Pannonia and celebrated on coins of Constantine with SARMATIA DEVICTA ("Sarmatia conquered"). At the same time the two Caesars, Crispus and Constantine Junior celebrated their Quinquennalia on coins with a laurel wreath enclosing the words VOT X and legend CAESARVM NOSTRORVM ("our Caesars"). The vows were suscepta, five years completed and looking forward to the tenth anniversary. A second war against the Visigoths occupied most of AD 323, before Constantine embarked on his final showdown with Licinius, ending with the defeat of Licinius at Chrysopolis later in year. Licinius managed to survive until AD 325, when he was executed by Constantine.

In the final, rare, issues from London, another new coin type was introduced, showing a turreted gateway and legend PROVIDENTIAE AVGG (for Constantine) or PROVIDENTIAE CAESS (for his sons) ("To the providence/foresight of the emperors/Caesars"). Included in this coinage was another of Constantine's sons by Fausta, Constantius, born AD 317. Both Fausta, with reverse SECVITAS REIPVBLICE (The security of the Republic") and Constantine's mother, Helena, with reverse SALVS REIPVBLICAE ("The health of the Republic"), featured on this coinage, with the title of Augusta. This family harmony did not last. In AD 326, Crispus was accused of treason by Fausta and Constantine, quick to rage, had him executed. When it transpired that the accusations were false, he had Fausta thrown into a vat of boiling water.

With the provinces of Britain secure for the time being and, possibly, much of the garrison withdrawn to reinforce the Rhine frontier, the London mint was closed in AD 325.

1. SACRA MONET VRB AVGG ET CAESS NN at Rome. The legend can be translated as the "The Sacred Money of the City (i.e. Rome) of our Emperors and Caesars"

2. Note the mispelling of the word Beatissimo - this occurs at several other mints as well.

3. Since the reign of Augustus 300 years earlier and the designation of Caius and Lucius Caesars as his heirs.

4. In Diocletian's Tetrarchy, the east was under the auspices of Jupiter (Jove) and the west under Hercules, the respective emperors and caesars of each half therefore being either Jovians or Herculeans.

5. This was not the case at other mints under Constantine's control.

6. A title also given to Constantine as well but only used in the eastern part of the empire where Galerius held sway.

7. However, coins of Licinius and his son Licinius II, continued to be issued at the mints in Gaul (Trier, Lyons and the new one established at Arles by the transfer of the former Maxentian mint of Ostia) almost up to the final break with Licinius in circa AD 320

8. The daughter of Maximian, who Constantine married in AD 307.

9. Right to the end, Roman rulers maintained the fiction that the empire was still a republic, of which they were the elected rulers

 Diocletian

IMP C DIOCLETIANVS P F AVG
IMP DIOCLETIANVS P F AVG
IMP DIOCLETIANVS P AVG
IMP DIOCLETIANVS AVG

D N DIOCLETIANO BAEATISSIMO SEN AVG
D N DICOLETIANO FELICISSIMO SEN AVG
D N DIOCLETIANO P F S AVG

IMP C MAXIMIANVS P F AVG
IMP MAXIMIANVS P F AVG
IMP MAXIMINAVS PIVS AVG
IMP MAXIMIANVS P AVG
IMP MAXIMIANVS AVG

D N MAXIMIANO BAEATISSIMO SEN AVG
D N MAXIMIANO FELICISSIMO SEN AVG
D N MAXIMIANO P F S AVG

FL VAL CONSTANTIVS NOB C
CONSTANTIVS NOBIL C
CONSTANTIVS NOB C

IMP CONSTANTIVS PIVS FEL AVG
IMP CONSTANTIVS P F AVG
IMP CONSTANTIVS AVG

DIVO CONSTANTIO PIO

C VAL MAXIMIANVS NOB C
MAXIMIANVS NOBIL CAES
MAXIMIANVS NOBIL C
MAXIMIANVS NOB CAES
MAXIMIANVS NOB C

IMP MAXIMIANVS PIVS FEL AVG
IMP C MAXIMIANVS P F AVG
IMP C MAXIMIANVS P AVG
IMP MAXIMIANVS P F IN AVG (IN = Invictus)
IMP MAXIMIANVS P F AVG

SEVERVS NOBILISSIMVS CAESAR
SEVERVS NOBILISSIMVS CAES
SEVERVS NOBILISSIMVS C
SEVERVS NOBILIS C
SEVERVS NOBIL C

IMP C SEVERVS PIVS FELIX AVG
IMP SEVERVS PIVS FELIX AVG
IMP SEVERVS P F AVG

GAL VAL MAXIMINVS NOBIL C
GAL VAL MAXIMINVS NOB C
MAXIMINVS NOBILISSIMVS CAESAR
MAXIMINVS NOBILISSIMVS CAES
MAXIMINVS NOBILIS CAES
MAXIMINVS NOBILIS C
MAXIMINVS NOBIL C
MAXIMINVS NOB CAES

IMP MAXIMINVS P F AVG
IMP MAXIMINVS P AVG

FL VAL CONSTANTINVS NOB C
CONSTANTINVS NOB CAES
CONSTANTINVS NOBIL C

IMP CONSTANTINVS P F AVG
IMP CONSTANTINVS AVG
IMP CONSTANTINVS AG
CONSTANTINVS P F AVG
CONSTANTINVS P F IN AVG
CONSTANTINVS P AVG
CONSTANTINVS AVG
CONSTANTINVS AG
IMP CONSTANTINVS MAX AVG
IMP CONSTANTINVS IN AVG (IN = Invictus)

IMP LICINIVS P F AVG
IMP LICINIVS P AVG

FL IVL CRISPVS NOB CAES
FL IVL CRISPVS NOBIL C
IVL CRISPVS NOB C
CRISPVS NOB CAESAR
CRISPVS NOB CAES
CRISPVS NOBIL C

FL CL CONSTANTINVS IVN N C
CONSTANTINVS IVN N C
CONSTANTINVS IVN NOB C

FL IVL CONSTANTIVS NOB C
FLA CONSTANTIVS NOB C

FL HELENA AVGVSTA

FLAV MAX FAVSTA AG