Not Luton, but I remember seeing 35 diversions at Hurn (Bournemouth) on my way to work one morning about 1972.
All of Courtline's 1-11s, 4 or 5 Lufthansa 727 or 737s, many Dan-Air Comets and 1-11s, TMAC CL-44, 2 Laker DC-10s, Some Tridents and many others I can't recall.
Every available bit of space was used including the BAC factory site.
Wish I had taken some photos.