All, thanks for the help!
I have tried Injector cleaner not sure if its helped. The car has covered 91K miles, so I will have the injectors pulled out and ultrasoncally cleaned (£100 sounds reasonable) , I feel it needs this as the car hesitates slightly at times also.
As to the question regarding the rain, it appears to do it in any weather.
I havent as yet checked the plugs.
Changed the front pads today, for mintex items, which seem very good and only cost £34.