brit pat was on the hds and other razors 55 onwards..yours could be 55 due to not having the ll on the bottom.. https://www.mr-razor.com/
Here is an ad from 1956 showing the British style Rocket razor sold both as a Rocket and as a one piece.
Here is an example of a Flare Tip razor that was never sold or referred to as a Rocket though collectors still do refer to it as such.
Oddly enough, I own the same type of FT. Mine is a strange bird; it has the Brit Pat # in the blade tray, but does not have "Made in England" stamped on the underside.
my canadian gold wash rocket.brit razor, canadian case..nickel rocket beside it .gold wash is hard to see in my light ..
Wonderful write-up! I am not going through 21 pages of comments, but if nobody has mentioned it yet, there appears to be a typo in the serial number of: "#6: Aristocrat Jr./#48; this uncommon razor could predate both the Rocket and Aristocrat Jr.. It has a knob that doesn’t recede into the handle but functions like an American Super Speed. It also has the 1/8” thick heavy flat brass plate that the blade rests on like the Aristocrat Jr.. More features of these razors are the lack of end caps and un-notched post reminiscent of a 1947 Super Speed, this is the only un-notched Rocket type that I know of. These share the same head design as the English Aristocrat #21. A Strange hybrid that came in either a white or blue Bakelite case. I think the blue cases were for sale in England and the white ones indicate it was for the Australian market. These have BRIT PAT NO 403030 stamped under head and weigh 62 grams." I believe that should be BRIT PAT NO 430030 (not 403030).