BEagle
I don't know which airline wrecker flew with, nor which mark of Trident, although the reference to Gibraltar suggests it may have been BEA.
If it was BEA, talk of a M0.88 cruise and a Vmo of 385 kts for a Trident 1 is somewhat over the top!
For the record all the Tridents in BEA/BA had an Mmo of M0.87, with the Tridents 1 & 2 having a Vmo of 365 kts (300 kts for a Trident 2 with fuel in the fin tank) and the Trident 3 having a Vmo of 350 kts.
M0.93 may have been demonstrated at base, but was way above the normal cruise mach number.