This is BS. I first ran across rumors like this some time back when I first began digging up primary evidence for my Masters. There is NO PROOF British Intelligence blew up refugee ships. The idea is absurd.
Now, they DID interfere with Jewish immigration into Palestine, mostly to protect oil industry properties in the Middle East. The Palestinians were busy selling land to refugees (no, the refugees did not take the future Israel by force), and this was freaking out other Arab centers of power, which were tending Nazi, anyway. To avoid more rebellions than the Nazis were already stirring up, the English schemed to limit Jewish immigration into the Middle East.
But blow up ships? No way.
It sounds like BS to me too.
To some of us, this is not news. Flail as you will.