I am adding my own answer to question. The service guy came and could not find the fault , he spent about 1 hour on it. Suggested take it to the dealers and see whether they can trace the fault.I then took it to Service force Ashford. Got a phone call from them that the thermo coupler i put in ( PATTERN ONE) was faulty ie it was loose in the fitting and the other thing was the switch assemly where when it was put on gas it did not always connect , so now its back in the caravan and working as it should Total bill £124
Robert
March 2009