By Susie Beever A historic painting of a former Tory PM was destroyed on Friday after being targeted by pro-Palestine protesters. The portrait of Arthur Balfour was defaced with red paint by activists at Cambridge’s Trinity College, with the group Palestine Action claiming members were involved. Lord Balfour was a leader between 1902 and 1905 and later signed the Balfour Declaration as Foreign Secretary in 1917. The Declaration was a public document stating Britain’s official approval of Palestine as “a national home for the Jewish people”. Footage was shared online by Palestine Action on Frid…