Ignition switch problem

My T plate Freelander has recently developed a fault whereby the ignition will not work. When the key is turned there is nothing at all. Dash lights are on and all electrics working.
It just won't start at all. All of a sudden it will start. No real pattern, sometimes 1st time then 5th etc, can also start after turning key all way and holding there, but again no pattern at all.
Its not starter, had it shorted today and started everytime so must be the barrell I guess.
Mechanic says you can replace without changing key etc, just replace the electrical bit.
Anyone know the part number and where to get one, or can i just clean some contacts or anything else really.
Cheers guys.

Popular fix to change the electrical switch on the rear of the ignition.

Take the cowling off, remove the plug and squirt it with wd40. Give it some up the barrel too.