Just found out that why Yesterdays Thomson B767 G-OBYG positioned down to Gatwick as TOM9019 leaving the LBA to PMI pax behind. It was for operational reasons.
The aircraft was needed down at Gatwick to operate the TOM092 long haul service to Cancun. The LBA Pax heading out to PMI were sent over the hill on buses in the evening and they departed MAN at around 21:00 last night on a replacement aircraft which was B767-300, G-OBYE.