Thanks Albas & everyone, this is the up date....
On my way home from work then on to the garage the light was flashing ever more frequently but very intermittently engine running ok. It failed the MOT

but I thought it would, not too bad however as they are only trivial things & not to scary it will probably cost about £100 to put it through & that is to include the test fee, the cat was rattling some previous owner had but a screw in it to try & stop it !
The flashing could be caused by fact that the car has a 'misfire' which was picked up on the emissions test, so that could be a coil or a plug ? that would explain flickering perhaps ? but you all know assumption in the mother of all ****ups