On 10 Sep, 11:45, robert wrote:
Have acquired an old pedestal drill with a
British Houston Thompson single phase 1/4hp motor
marked KF TD3205 type BS 2408

The motor start capacitor needs replacing but it has no visible markings
on it *due to several paint coatings !

With capacitor removed the motor will run with a hand start and I can
hear what I assume is a centrifugal switch clicking on spin up and spin
down.

Any advice on what size capacitor to buy and try ?

A 70 watt burner motor takes a 4 microfarad. Multiplying up a 1/4 hp
should be about 187 watts so try as a beginning 11 or 12 microfarad.
Make sure any cap you try is rated for mains ac. if it helps you could
use 3 of the burner motor caps in parallel. I got mine from Farnell
Components a few years ago