Relays work fine, I have disconnected the sensor on the radiator and they come on. Rad sensor has also been checked.

Ok so feel the water outlet of the radiator is it hot ?.
 
It should be , if not its not going thru.
 
Possible the water pump is knackered also

I wonder if there is a test that can be done to determine how much flow you have in a cooling system

over the years, we have had only a few cars with this mount of bother, and I fully understand the owners' frustrations
Overheating can be very difficult to find, as the 'obvious" problems are not always the only ones. The various pressure and chemical tests for a blown/leaking head gasket are never perfect. if they find "no leaks" thats not 100% certainty. if they find a leak, then that's 100% (chemical reactions dont lie) 
You cant really compare a rebuild of an engine like a 3SGTE with a bolt-in second hand 2GR. different deal totally.
The biggest problem is the cost of labour and the man hours needed. In this country, any reputable mechanical shop charging less than about $90/hour is losing money. it  takes us about 40 hours to remove a 3SGTE, overhaul it fully (internal machining etc) and then put it back in. Add to that cost of parts and $7-$8K appears quickly. I doubt many others can do it this quickly as we are one of the only shops that do it all in-house, and have spent years building special tools,. jigs etc to do these cars. 
Generalist mechanics often look at these cars and run away and hide, because other jobs are much more profitable. They are not incompetent, they just dont want your work. Taking a MR2 to these people for major jobs like engine or transmission repairs is just asking for trouble as they get caught every time. Dealership can often be the worst, because 75% of their staff have no experience other than near-new cars, and these dont have any "old car" issues like i constantly see appear on these forums 
I hope this puts you all in the picture
 
 

i dont think the 3sgte is the hard/expensive part about working on an mr2.. i think it's cause the MR2 makes it friggin impossible to get to anything... and the rear layout means the engine bay sees a lot of heat which isn't great for electrics, hoses or detonation issues....
 
it's just part of owning the car... it's a bit like a ducati, it'll make a mechanic out of you because you either so you can work on it or so you know what your mechanic is doing and if hes bullshifting you.

Road and Track

over the years, we have had only a few cars with this mount of bother, and I fully understand the owners' frustrations
Overheating can be very difficult to find, as the 'obvious" problems are not always the only ones. The various pressure and chemical tests for a blown/leaking head gasket are never perfect. if they find "no leaks" thats not 100% certainty. if they find a leak, then that's 100% (chemical reactions dont lie) 
You cant really compare a rebuild of an engine like a 3SGTE with a bolt-in second hand 2GR. different deal totally.
The biggest problem is the cost of labour and the man hours needed. In this country, any reputable mechanical shop charging less than about $90/hour is losing money. it  takes us about 40 hours to remove a 3SGTE, overhaul it fully (internal machining etc) and then put it back in. Add to that cost of parts and $7-$8K appears quickly. I doubt many others can do it this quickly as we are one of the only shops that do it all in-house, and have spent years building special tools,. jigs etc to do these cars. 
Generalist mechanics often look at these cars and run away and hide, because other jobs are much more profitable. They are not incompetent, they just dont want your work. Taking a MR2 to these people for major jobs like engine or transmission repairs is just asking for trouble as they get caught every time. Dealership can often be the worst, because 75% of their staff have no experience other than near-new cars, and these dont have any "old car" issues like i constantly see appear on these forums 
I hope this puts you all in the picture

 
Oh this is so well said !!!!!!!!!!!!!!!!!!!

Yes, that is well said. Cooling issues with MR2's are probably the most frustrating I've ever encountered.

I have spoken to terry a few times and he's a good guy. Doesn't piss in your pocket and knows his business with these engines. He also has a very promising gen 2 long block that might be making its way to Sydney for my car.

Saw your car @ RS last night btw. Was dark & cold, so didn't have a close up peek though.

Gen 2? What happened to the 2GR