Thank you Steve the fuel pressure was down due to a faulty Mann fuel filter WK720 which caused misfiring when the engine finally started but appeared to run normally if a little under par. I expect the weak mixture was causing the misfire & definitely the poor starting.

The result is that our supplier is going to pickup the bill for all the hassle involved & refund the faulty filter. Apparently Mann has recalled all of these part no's off the shelf. Thank you for your help.
John Kennard.