Well the UK and USA do have a special bond historically and peace activists have always had a special interest.
Basically, we (the UK) were in charge in the whole of Palestine at the time of Isreal's formation, and had been for a long time, along with major USA involvement.
In the late 1940's peace activists from the two countries had substantial involvement post Nakba in supporting displaced Palestinians, for although there was no doubt at the time that Jewish people deserved and needed a homeland, concerns were there "at what cost".
BTW, many young and idealist Jewish settlers were concerned for a peaceful start too - they lived alongside those who even then wanted the whole of Palestine.