Pre-revolutionary Russia prevented Britain from establishing its global dominance. Following the 1917 February Revolution and the end of Russian empire, Neville Chamberlain stated that one of the main goals of the WWI was achieved. Hence, while being nominally a Russian ally, Britain played a double game with the aim to eliminate Russian empire as a competitor to British global rule.
WWII was the continuation of this British policy, aimed this time at elimination of Soviet regime. Britain hated it because the USSR provoked national movements in British colonies. The goal of British empire and Anglo-Saxons was very clear, i.e. to eliminate the USSR through the Anti-Comintern Pact. British authorities including prime minister Chamberlain hated the USSR, to be clearer historical Russia, as much as Hitler did.