Frankenbike is not a respectful bike name. In some ways, Frankenbike is misnamed. You see, Frankenbike is a Falcon. Falcon made their reputation when Ernie Clements designed their bikes and managed the company in the 50's through the 70's. It was from Ernie that Falcon derived its logo of a Falcon flying underneath Olympic Rings (Ernie won a silver medal at the 1948 Olympics). Among other things, Falcon built race bikes for Eddie Merckx, arguably the greatest racer of all time. Falcon still exists, though they mostly build low end stuff nowadays.
Frankenbike was a "middle of the line" Falcon, with Reynolds 531 plain gage tubing, Cinelli handlebars, and low end Campagnolo shifting equipment, along with a steel crank, half step gearing, and tubular tires. It was quite light when so equipped (about 23 lb). Unfortunately, while tubular tires have a sweet ride, and are tougher than their reputation, they're expensive, there's not much help at the LBS, and I'm not good at repairing them. Armadillo clinchers are much better for going to the store.
Frankenbike may not have quite been an aristocrat in the bicycle world, but it had aristocratic relatives, and has nothing to be ashamed of. And that makes a difference. I know where to find new decals, and I've got Campagnolo tubulars and toe clips waiting for it. With quick release couplings (not easy to find) and fasteners, I'll be able to convert it back and forth from internal gear utilibike to quick single speed in minutes. In that form, with a light alloy crank, it'll be just under 20 lb.
As I write this, I can almost hear Rantwick singing "God Save the Queen." It's a Commonwealth thing, and an entirely different British bike approach than that represented by Pashley...
The Falcon head badge incorporated Ernie's name into it, along with the Olympic Rings in honor of his silver medal as part of the British road race team in the 1948 London Olympics. Bob Maitland was another notable member of the team. While, sadly, Ernie passed away in 2006, Bob is still alive, having won the Master's World Championship in 1989 at the age of 65. It seems that cyclists hang around a good long while.
Falcons used a unique "wraparound" seat stay. It's one way you can recognize a 60's or 70's Falcon from any other bike, regardless of how it's been repainted. The Falcon Merckx bikes used this feature, though they were painted in Orange and not identified as Falcon frames.
Often mistaken for a model name, "San Remo." It may have started as a model name, but Falcon stuck it on many distinctively different models ranging from low end up to top of the line. Just as Bianchi has "Celeste" as "their" color, the quintessential color for an old Falcon is a Robin's Egg Blue color. Personally, I like the red and it turns out that, purely by accident, all the bikes I ride regularly are that color. Still, the blue IS pretty.
GB was an English component supplier of the period. See here for more details. GB stands for "Gerry Burgess," not "Great Britain," though that'd be apropos as well.
Frankenbike used Reynolds 531 plain gage (not double butted) tubing. There's not much of the sticker left, but that'd be what it would indicate if you could read it. In the days of steel bikes, double butted 531 was the HM carbon of its day, and, along with the hand lugwork, indicated the bike was a true aristocrat. It also forges a Jaguar connection. The Jaguar XKE used Reynolds 531 tubing in its front subframe. There's more about 531 tubing here. You'll note there's not really any rust on Frankenbike's frame (there IS rust on things like the crank and braking steel components), despite the paint having seen better days. It's ready for another 40 years of faithful service. A little paint & polish, and it'd be a thief magnet.