Re: Just move
Fortunately Hursley House is a Grade II listed building and has a lot of other history associated with it (such as the development of the Spitfire) so it is safe from any sort of development involving significant changes to the house/grounds. Whether IBM stays there is a different question but given that their offices in nearby Basingstoke have been shut down they might have problems finding an alternative site anywhere nearby and moving a long way would probably entail a lot of staff leakage.