Hi Gareth, the garage said it could be crankshaft sensor, waiting to hear from them today,probktwas there before flywheel started to go ,rattle on start up .
They took old starter motor out and tested it on bench ,said it was turning but maybe not fast enough to turn engine, fitted new starter but same problem. When you turn key engine turns breifly then stops just the same as if you had a flat battery,the dashboard lights flicker same time . battery been checked it's good . problem is just spent £700 on flywheel and gearbox oil change and can't really afford to be spending a lot more on diagnostic ,I'm a taxi driver and been off road for a week already.