It seems like an important story, but the information was received by the Brits from an unnamed source, so it's difficult to guage it's accuracy. Here's some more info from the BBC version of the story.

In the document, written on 30 June 1976 when the crisis was still unresolved, DH Colvin of the Paris Embassy writes of his source: "According to his information, the hijack was the work of the PFLP, with help from the Israeli Secret Service, the Shin Beit.

"The operation was designed to torpedo the PLO's standing in France and to prevent what they see as a growing rapprochement between the PLO and the Americans."

He adds: "My contact said the PFLP had attracted all sorts of wild elements, some of whom had been planted by the Israelis."

The documents also reveal that the British government debated whether or not to praise the Israeli raid after its completion.

The BBC article concludes with:

The file does not make it clear how seriously the government took the claim that Israel also may have aided the hijackers.

And it does seem that's the relevant question, which one hopes might be answered by the British. Was the unnamed source taken seriously, and more importantly if so, why.

There's a lot of conflict just now between the Israelis and the British over the boycott. This may be a part of that somehow.

Edited to add: There's a more extensive article on this at the Scotsman, UK. It says that the source was "a contact at the Euro-Arab Parliamentary Association."

It's always difficult to know about these sorts of stories; there are a variety of conspiracy theories that circulate regularly, but on the other hand, Shin beit and Mossad do have a certain history...

Know your enemy well, for in the end that is who you become. ~~Old Chinese Proverb