There's an interesting piece here...
Concorde: story of a supersonic pioneer By Kenneth Owen, Science Museum (Great Britain)
Dr Hooker's argument that it makes more sense leaving the dead weight of an APU on the ground rather than carry it around at supersonic speed makes sense. (I presume this is the late Sir Stanley Hooker)
"It surprises me to hear you people asking for equipment to be carried around at supersonic speed when it could be left on the ground. It cannot be economical to carry this stuff around at Mach 2.2 just to save a little labour cost at the airport. On the possibility of aircraft damage, you must organise yourselves so that you do not damage the aeroplane. [Damage by engine starter vehicles to aircraft, and the labour costs involved had been mentioned by Eastern Airlines]. The problems you are imposing involve us in developing entirely new equipment at vast cost. The equipment will be baked consistently at 150 deg C. The problems of certification must be worked out for this equipment and may alter the case considerably."