The office is in the railway station building so anyone catching a train in Milton Keynes would be hard pressed not to notice it. Since most boaters won't catch trains in MK I thought I would post a picture of the front door. The visuals around the door are interesting but don''t expect to gain access. The door is firmly locked most of the day and I didn't see any sign of a receptionist. I think they don't expect or want to get any casual visitors.
CRT Headquarters Milton Keynes
Being a long time resident of the area I remember the station being constructed and it being used for filming Superman IV in the late 1980s. If you want to see the CRT offices featuring as the Daily Planet offices go to here. It was the last Superman film that starred Chistopher Reeves.
(Poster taken from Wikipedia)