221 was originally a hut on the perimeter of Heathrow along side the Bath Road where BOAC flight and cabin crew reported. I think because the huts were numbered rather than named.
The flight report centre moved to Terminal 3 at some time in the 60's [before my time] but the name 221 continued to be used until BA moved to Tristar House.
Even recently the term '221 divorce' was used by us older members of the community to signify the seperation of 'temporary couples' returning from a long trip. If you get my meaning
