Bought this Major pack M1b BP tanker for £1 today. I know it's not an HTF but it's clearly been played with and I'm pretty sure it's an earlier version, given the hole in the front. Not sure how early though..
The 'BP' Autotanker was introduced in 1961 and deleted in 1966, it is often included in collections as a 'Regular Wheel' range model because of it's size, but is in fact from the 'Major Pack' range.