For Sale: 1950's Carlton Catalina single speed

It's not slagging off, it's an honest opinion with information that would help a potential buyer make a decision.

As a general rule, if you ride a normal bike, you have to have two *independent *braking systems: one “which operates on the front wheel”, and one which operates on the back. (PCCUR r. 7(1)(b)(ii))
So no, you're wrong. 1 brake is allowed on a fixed gear bike of course

By law, fixed-wheel bikes (i.e. bikes where “one or more of the wheels is incapable of rotating independently of the pedals”) have to have a front brake. (PCCUR r. 7(1)(b)(i))
I won't keep my opinions to myself when people are trying to fleece buyers. That's the great thing about forums, they protect everyone involved!

And I think 99.9% of people on here would consider 700c in a 27" a bodge, especially when wheels and tyres are readily available and cheap as cheaps. 'custom' doesn't have to be shoddy...

If you ride your bike on a road and it doesn’t have the necessary brakes, or it does have the brakes but they’re not in efficient working order, you’ll commit an offence. It doesn’t matter whether you *know *about the problem with your brakes – you’ll be guilty just by riding on the road. (PCCUR rr. 6, 10; RTOA s. 91; James v Smee [1955] 1 QB 78, 90).
It’s also an offence to “cause or permit” someone to ride a bike on the road when it doesn’t have the necessary brakes, or the brakes aren’t in good order. So if you lend your bike to someone else, and they are caught riding it on the road without proper brakes, you could commit this offence – or (possibly) if you permit your child to ride their bike on the road without proper brakes. But if you’re not the person doing the riding, you will probably only commit this offence if you *knew *about the problem with the brakes (or “shut your eyes to the obvious”). (James v Smee, above, 91)

Also inconsiderate selling a bike to an unsuspecting buyer that's unsafe and could leave them open to a fine.