In these times the British were overtly pro-Palestinian… So this conclusion is obvious : everybody blames Irgun yet they did NOT revindicate. Why would a persecuted people commit an “act of terror” against the very powerful British that had them in their power ? The British Army HQ had a small reactor in its HQ for obvious military purposes (making neutron sources & small Pu bombs close to a strategical area and likely giving also some to Palestinian militants secretly).
It’s a pebble bed cylinder.
Another case for a pebble bed in a building : Le Pen’s.