I think TU144 has got it right.
In the UK I believe that it goes like this
BPK5T
BPK is the end of the SID
5 is the revision number
T is the runway designator - in this case RWY27 at EGLC.
There are other BPK departures for other airfields in the London area e.g. BPK7F is for EGLL