First off, really sorry for asking a question and then not acknowledging your responses.
Not being an ass (honest), just been busy.
The battery charger is a Halfords unit that has settings for standard and gell batteries, plus there's a bike or car switch. According to the writing it will condition gell batteries and won't overcharge.
I've tried shorting the starter solenoid and that didn't work. Other than the sparks as you said
I did try the car setting on the charger to give it some more amps and it did turn the engine over for a few seconds then same fault as before.
So my next plan is to get some jump leads and connect up my car battery.
Looks very much like the battery is stuffed as suggested.
I must admit that whilst I normally leave the charger on over the winter period this time I didn't bother. Just charged it a couple of times when I thought. As it was ok last week I assumed all was well.
Seems not.
It's odd that the ignition lights seem bright before and after I try to start it. It's only when I press the starter that everything goes dim. Guess it's just that the battery can't supply the big amps to turn the motor over. Oh, I've decided to ignore the noise from the ignition switch for the moment - if it is the fault I'll know when I connect the car battery
Thanks for the help so far.