Ascension is the Atlantic version of Diego Garcia , British Dependency partly/mostly leased to the Americans as a 'milaterry faciliteh'. Ask any awkward questions of the Yanks and they refer you to the F&CO, Ask the F&CO and they tell you to speak to the US .
If I recall correctly the airfield -Wideawake Field was built in WW2 as part of a south about route for US aircraft to get to the middle east via Brazil and Africa.
I worked for a UK company that had interests there and back in the day the only practical way on and off was via RAF flights that took passengers but only from UK Gov or related organisations and along with these was NASA tracking station and the USAF who leased the airport and related facilities. Ascension was very very important in the Falklands war , basically it could not have been contemplated without it.
It is an irony that just after the UK Government shells out for a lovely new runway/airport in 'neighbouring' St Helena the Ascension islanders lose their runway. Of course if oil/extremists/anyone DT doesnt like appear in somewhere like DRC or Angola or Brazil the runway will be repaired in a heartbeat but theres no sign of that.
Given their combined population of about 5500 People the three S Atlantic islands St H , Ascension and falklands have cost the UK tax payer one hell of a lot of money in the last 30 odd years just to cling on to vestiges of Empire. Still no doubt Liam Fox will be keen to negotiate a trade agreement with them