Just a short up-date on this. The new fuel filter appears to have cured the P1188 problem....so far. However, it was a non-start the other day and it was found that the filter was just about empty of fuel. He has dismantled various bits and pieces on the fuel side and remade ensuring no air leaks etc. So, its a question now of wait and see. The next step will probably to replace the primer and filter housing as previously suggested.
Thanks Steve Shaw and Tony for your recent inputs.
Regards
Pete M