Primrose Hill coal hole cover plates

Out wandering about in Primrose Hill the other week I noticed quite a few unusual names and designs on the coal hole cover plates embedded in the pavements there. Most cover plates have patterns on them to stop them from being slippery underfoot. Many just have patterns on them but canny ironmongers realised it was a good way to advertise themselves.
As you see these ironmongers are not all local to the area – Abbott of Great College St, West Bros of Marchmont St, Young of Davies St, Persons of Notting Hill, Watkins of Regents Park (the most local), Philp of Fitzroy Sq (oops, I now see I have put two of those in there!), Davies of Clapham &Camberwell, Ward of Edgeware Rd and Wood & Barrets of Tottenham Ct Rd. I didn't see any company names from addresses in Chalk Farm Road or Camden High Street, which seems odd.
The one I like best is the one that reads, Charles's Safety Plate, by patent act Vic, which I assume is a ref to Queen Victoria. This needs a bit of research. And also some better pics because the light was fading by the time I reached this terrace where almost every house had one of these outside.
Also notice the second pic which shows one of the Abbott covers embedded into two lovely pieces of Yorkstone. This is not the only cover I noticed where a feint keyhole or toilet bowl shape is evident around it. Does anyone know how/why this shape was made?
Another ironmonger, not shown in this collection, was repeated a lot in various different designs. I will post about that company sometime soon once I have put them into some kind of chronological order and done a bit of research.
See also the coal holes of Warwick Square and the contemporary ones in North Audley Street.