I wouldn't say a bust type (even trabeate) not in RIC necessarily indicates a visit from Constantine, as many of the mints in the West during this period occasionally have some different or special bust types. London, specifically, has a series of trabeate bust types, circa 315 for his 4th consulship. Also, Lyons is not well represented in RIC, which is why Bastien is an important reference. Even so, coins turn up not in either reference, like this coin. I don't want to dump a ton of pictures into this topic, but an example of another interesting bust from about the same time (315- 316) from Arles. Next, a special bust type from Trier, also from about the same time. So, if these mints issued special types because of personal visits, Constantine was very busy bouncing around in 315- 316.