Brian Rollo has supplied these pictures of a model box, found and opened up in March 2011.
The packing note identified this as a 1/12 scale HST Jet Provost.  It was sent from RAE Farnborough and was addressed to Tom Smith, then Deputy Chief Wind Tunnel Engineer.  The note is dated 16 January 1967, which is about a fortnight after I joined BAC (Operating) Ltd, as it then was, in Wind Tunnel Department.

caption by Cliff Elliott