They have fought for different reasons:

• The British knew of the plan in 1982 to assassinate Shlomo Argov, the Israeli ambassador to London, but the Israelis were not warned.

• The Israelis knew the Palestinian satirical cartoonist Nagy el-Ali el-Adami was to be assassinated in London in 1987 by his countrymen. The British were not told because Israel did not want to expose its double agents in the PLO's London-based cells.

• In 1986 suitcases of explosives were sent to Israel from locations in Europe. One came from Heathrow. It became clear, according to Mossad sources, that the British knew of the suitcase but did not see fit to pass the information to the Israelis.

• The former MI5 officer David Shayler has also said it received warning from a reliable source of the planned 1994 bombing attack on the Israeli embassy but the information was not passed on.

And much more:

https://www.independent.co.uk/news/world/mi5-was-feuding-with-mossad-while-known-terrorists-struck-in-london-1101024.html