Of course the hostility of the British establishment toward Jewish immigration into Palestine since long before the notorious 1939 White Paper on the subject is well-known—even King George VI wrote that year to say that he was “glad to think that steps are being taken to prevent these people leaving their country of origin”—nonetheless this is the first indication of the violent lengths to which post-war Britain was willing to go in order to appease the oil-rich Arab states of the region. For it now emerges that in late 1946 the Labour government of Clement Attlee asked MI6 for “proposals for action to deter ships masters and crews from engaging in illegal Jewish immigration and traffic,” adding, “Action of the nature contemplated is, in fact, a form of intimidation and intimidation is only likely to be effective if some members of the group of people to be intimidated actually suffer unpleasant consequences.” Among the options contemplated were “the discovery of some sabotage device, which had ‘failed’ to function after the sailing of a ship,” “tampering with a ship’s fresh water supplies or the crew’s food,” and “fire on board ship in port.” Sir Stewart Menzies, the chief of the SIS, suggested these could be blamed on an invented Arab terrorist group called The Defenders of Arab Palestine.
So according to the article I linked the only reason it was blamed on a terrorist group was because it failed but the original intention was to appease the Arab nations.