Thank you Johnny F@rt Pants and DaveReidUK.
Do you know if this was a purpose built facility or is it based on something perhaps more 'historical'? By this I mean, as a complete novice in such matters it would seem to me that very large aircraft like the ones described on their website would need a substantial runway to land etc. To purpose build one in the Cotswolds would seem to be quite a financial/technical undertaking.
So, I'm wondering if maybe it was founded on some previous military facility or infrastructure for example.