I think I am an idiot. I wanted a spare set of plugs so I took mine out to take to the motor factor shop. When I got there I found they were Champion L82C. A short reach plug. I can only assume these were the ones that was in the bike when I got it. I would have put them in to prevent things dropping into through the plug hole.
I see I bought some NGK B7ES but the Haynes manual states NGK B7HC.
I am a bit confused perhaps I need to go back and buy some B7HC plugs.
On the positive side, the GF ran fine on the L82C. Just a forgiving bike I suppose.
John