IT WAS THE IGNITION SWITCH!!

After 10 days standing idle, the old girl sprang to life this afternoon.

Thanks to everyone for the advice. I now have a very definate 'click' when it turn the key to start, and it starts on the button.
TIP: After 10 minutes trying to work out how to remove the screw holding the switch in, I found out that if you unlock the barrel you can turn the shaft so that column is angled so you can access the screw, without resorting to bending you prised drivers.
Thanks to Rubjonny for the tip on priming the pump 10 times before starting, as I had replaced the fuel filter beforehand, and was crestfallen when it initially would not start. PHEW!!

Here's a picture of the offending article.
