Issue resolved today 
Went there armed with a LS Valve and two AAV's, put the AAV's in place of the two manual AV's and put the LS Valve in I think the flow pipe but may have been the return I can't remember
Filled the system back up and the same thing happened, rads stayed cold on the two pipe circut
Back up in the loft I went and shut the LS Valve down, the water started flowing in the direction that I wanted it too
After a lot of further bleeding of the 3 rads on the two pipe circut I had warm rads and then hot rads.
I balanced them and then went back up into the loft to open up the LS Valve to get the water flowing down the other circut, one by one they came up to temp nicely
Thanks all for advice, couldn't have done it without you
Went there armed with a LS Valve and two AAV's, put the AAV's in place of the two manual AV's and put the LS Valve in I think the flow pipe but may have been the return I can't remember
Filled the system back up and the same thing happened, rads stayed cold on the two pipe circut
Back up in the loft I went and shut the LS Valve down, the water started flowing in the direction that I wanted it too
After a lot of further bleeding of the 3 rads on the two pipe circut I had warm rads and then hot rads.
I balanced them and then went back up into the loft to open up the LS Valve to get the water flowing down the other circut, one by one they came up to temp nicely
Thanks all for advice, couldn't have done it without you
