ok, grove garage is good I have used them but a long time ago! as regards the "silly question..... when you turn the key to start it in the engine running position do you hear the fuel pump prime then STOP?" if it goes continuously the ECU is functioning but in limp mode, if it doesn't go at all the ECU can not control the engine (for a variety of reasons) so will not start it up!

not going to be in London till the last half of august so if still stuck let me know! I can however email you the wiring diagrams for the fiesta RST.