Question - Any idea what this may be near peterlee in the northeast

[lee_n_co]

hi was driving along the A19 near Peterlee, in the north east of England and noticed some large aerials, and was wondering was it a old communication centre or something been used now, I was going to go back and have a closer look but wanted to see if anyone knows what it is 1st .... looked on google maps ..
https://www.google.co.uk/maps/@54.777196,-1.3659572,56m/data=!3m1!1e3 ...
has anyone got any idea what this is??

 

[Yorrick]

To the West of the road is Mill Hill Underground Reservoir. To the East of the road is a mobile phone mast. Both are still live.