So I ended up swapping the (assumed) faulty No1 injector with No 2. It wouldn’t fire up at all. Did a little bleeding etc to no avail. I assumed that this means a bad injector and a bad No 1 cylinder ! I swapped it all back to original and it still would fire up

Messed about a bit and ended up toggling with the engine kill lever and it decided to start and tick over on the two original cylinders. I felt I had to do the swap out the No1 & No 2 again and it started. Cracked each fuel nut above the injectors and believe it or not all cylinders firing as there’s a definite change in tick over with all three.
I’ve since noticed small amounts of black oil splatter coming from the back of the No 1 cylinder along with smoke which presume is old shite burning of as it’s not been working for so long. I’ll upload a photo so it makes sense

it could well be previous diesel from all the bleeding