Hello all, finally I have a positive update!
After removing the intake to clean it out and check the swirl flaps, we changed the cambelt at the same time. Unfortunately when it was put back together it had issues starting. I took the car to Simply Alfas in Stourbridge to have the problem properly diagnosed.
Cambelt timing was checked and was fine. They confirmed fuel to the rail and injectors but recommended having all the injectors checked to confirm they were functioning properly. They were sent of to a testing company who found various faults with 4 out of the 5 injectors. I decided to have them all reconditioned which wasn't cheap at £110 each but once they were refitted to the car, after a few cranks it started. This was very frustrating for me as I had all 5 injectors tested a couple of months ago by another injector company due to a clattery smoky start-up , and paid for 2 of them to be refurbed! Clearly, something wasn't diagnosed or done properly.
I've been using the car for a couple of days and it starts fine, no clattering or start-up smoke any more !
So the car is now in good order, new cambelt kit, cleaned out intake and 5 refurbed injectors.
My next stop now is Gus at Alfatune for a remap I think.