The roof of F core penthouse. The three flues from the boiler house are in front – two larger ones the same size and one smaller one – these rise the entire height of the building. The size of the flues relates to the three original boilers – two large and one smaller but converting from heavy fuel oil to gas may have seen these metal stacks replaced as they look fairly new.
Behind the flues is one of the mobile masts – the highest point on site – and the mast’s control cabinet. The mobile operators paid rent to OS to site them here and I presume they used OS power but apart from that, were entirely self-contained installations, with no link to any OS comms infrastructure.