I can confirm the info given by xtypeman. My father who had been a Jersey based Captain with B(E)A from '58 to the base closure in ca. '74 was on that Tri-star flight in the late 70s which was sent to clear the back-log after a foggy spell. I don't remember if he was operating or positioning (I think the latter) as he was a commuter by that time on the T*.
All went well until the time to unload the pax when it was found that the tallest steps didn't go high enough so a pair of Dak steps was found which were strapped on the top to allow egress! There were no baggage container handling facilities either so the bags had to be loose loaded under nets.
The T* was severely weight limited on arrival allowing not much more than 100 pax to be carried inbound, but outbound it could manage the complete 330+ capacity at the regulated TOW with fuel only for London.
I think it was used one at least one more occasion but by then the required ground handling equipment was in place.
I well remember in the mid 60s when I worked on the ground there having several hundred stranded pax sleeping in the terminal in bad weather which often seemed to happen on bank holiday weekends. In those days Jersey was second only to LHR in the UK for aircraft movements but the largest aircraft were the Viscount, Argonaut and Vanguard and the majority Daks, Heralds and Vikings, how the holiday market has changed.