Hi, thanks for responding.
I should of added... I have been doing the speed tests on 3 different wireless devices - laptop, tablet and phone and get the same result on each. I will get the information you have requested and reply tomorrow.
Also worth noting that im doing all tests in very close range to router with direct sight.
I can only think that its some kind of interference (with it being sometimes 1Mbps and other times 20Mbps but no where close to wired speed)... but cant work out what is interferring.