Hi, i'm new to single speed bikes, i've got an old British frame and before i go too far I just want to ask whether it is suitable for a single speed road bike.

its got horizontal rear dropouts, so youll be fine.

If i want to go with larger wheel at the rear, how do i go about measuring the frame to know what size wheels it can take. I am only going to have a front brake, so i guess i am limited on the front by the brake position, and on the rear by the seat stay bridge???

it probably takes either 27" or 700c wheels, I would just use a set of 700c. you can definitely get far reach brakes that will fit a 700c front wheel

I've got exactly 14.5" / 368mm between the rear hub center and the seat stay bridge, and the same from front hub center to underneath of fork crown.

the only thing you should think about it the rear fork spacing.

That frame isn't very special at all (stamped dropouts, chainguard braze on). By the time you shell out to build that thing up from a bare frame, you could have bought a far better bike or a completed conversion with better bones.

Other than a potential issue with raleigh threading, everything should bolt right up. You can get nutted brake calipers at velo orange.

I've got 95mm on the front forks and 115mm on the rear. I'm guessing that they will flex to accept 100mm front and 120mm rear hubs?
As for the wheel diameter, the rear is around 365mm, wheel hub center to seat stay bridge, so if i want to fit a 700c which i believe is 362mm it will be very close to the bridge. I am not having a rear brake so i can modify the bridge slightly if it is touching the bridge. The front is again only about 365mm, and if the tyre touches the underneath of the crown there is nothing i can do. Should i go for a smaller front wheel?

If 700c wheels don't fit in that frame I will eat my eat and videotape it for you.

Am i correct in thinking a 700c with road tyres is 724mm dia?

If a 700c will fit in the forks, will i be able to get a front brake to fit?

700c rim is 622mm in diameter

it is possible your frame is made to fit 26" x 1 3/8 wheels which have a 590mm diameter.

Have a look through the Start Here thread

Pretty sure 700c is 622mm in diameter.

edit- tooo sloooooow

Just to totally beat this into the ground, 622/2 = 311mm Radius at the bead seat.

That leaves 50mm of space to fit a tire in. That's a lot of space. Enough to fit a 27" wheel in.