At the risk of coming over like a public service announcement...there was some speculation about the positioning of the track-ends on their conversions - check out the seat stays on the one you linked too, they are really close to back of the ends. Might raise BB height/ clearance issues. Also, judging by the dynamo (?) mount on the front fork leg it is very old frame and probably for 27" wheels...I'd say avoid if it goes much over £30.
At the risk of coming over like a public service announcement...there was some speculation about the positioning of the track-ends on their conversions - check out the seat stays on the one you linked too, they are really close to back of the ends. Might raise BB height/ clearance issues. Also, judging by the dynamo (?) mount on the front fork leg it is very old frame and probably for 27" wheels...I'd say avoid if it goes much over £30.