Just thought I would follow up and let people know what has happened.
Found a chap called Eric Ward who works at Walshes and lives near me. He had a look and at first thought it might be a sticking valve on the lift pump. So he removed it and gave it an overhaul. It was leaking from the diaphragm and the the valve needed replacing. This improved things.
Still seemed to be a problem so he replaced the splayers. That has made a real difference and I have to say the engine now starts quicker than it has ever done since I've had it.
The only thing left would be to overhaul the fuel pump. Eric was reluctant to do that, especially when I said it had been done 5 years ago by Walshes. He reckons it was probably him who had reconditioned it!
I was impressed by how quickly and easily Eric and Claudia, his missus who also works at Walshes, were able to remove and replace the pump and splayers. If you know what your doing these really are easy engines to work on. Having the right spanners also helps, we needed four types including Whitworths and BA (I'd never heard of the latter)