It's a square air box!

Spi then, the fan in the mpi is controlled by the ecu.

As suggested a few times already suspect a circulation issue..so best check the water pump is actually doing something useful...take off a suitable pipe (expansion tank perhaps) and see if the coolant pumps in relation to engine revs. I suspect the impeller is destroyed.

Start with the basics first before you get to some of the the hypothetical suggestions.
Test for +12v and 0v continuity at connector for fan switch on radiator.
If ok:
Link out connector for fan switch on radiator. If fan does not run then the fan or switch is duff.
Test the fan using a multi-meter connected to terminals and set for audible. Spin fan and the bleep if reading will be intermittent as it turns.
If ok:
Place switch from radiator in a pan of boiling water with multi-meter connected on continuity. If no bleep after a few minuets then It's duff.
If ok:
Start looking towards head gasket fail testing. Sometimes you can see small bubbles entering the header tank and smell fumes in it also.
After 4 years of standing it might have corroded? Water pumps fail from worn seals and rotted bearings.
The alloy impellers can corrode and effect flow rate but only due to a purer water mix. The head gasket would have been effected by this also.
How many miles has the car done and is it the original head gasket?

So, I now have an update on what's going on, car went into the garage this morning, I sent in the thermostat unit I bought aswell just incase they needed it, got called at 3pm, car ready to pick up, brilliant!!

Arrived to collect car, spoke to mechanic, he changed the thermostat because I bought one in and to his surprise when he took the old housing off. GUESS WHAT!! There was no thermostat inside ??? brilliant, so anyway, all replaced, fan is now working again. Now my only problem is is that the coolant temperature light comes on after two minutes of driving, I know it's not over heating, mechanic said it could be the sender unit? Cheers guys!

Our Arbath staemed the other day with steam out of the exhaust and after cooling wouldn't turn over...prob hydroliced idicating something major such as cylinder head gasket. Is this easy to do or is there a danger lots of other things will have gone wrong. Any advice gratefull.