Unfortunately, I have heard British people make jokes about the Holocaust. But they were members of the British National Party, a profoundly racist and in fact neo-NAZI organisation. I have never heard British people with mainstream political opinions make jokes at the expense of the Jews who were persecuted by Hitler.
I actually had the unpleasant experience of arguing with a member of the National Front (a militant racist/fascist group). This person was espousing the benefits of having a Hitler style dictatorship in Britain. When I asked him about the Concentration Camps, he said that it wasn't important because the people who died "were just Jews". Personally, I found this attitude deeply offensive. I have a great deal of sympathy for the Jewish people, who have been mistreated by their host populations for millenia.
Your uncle's failure to resent his government for their White Paper policies before or during the Holocaust or their treatment of the Jews prior to their withdrawal illustrates the British POV.
My uncle was a common man with a modest education. He was not interested in history, therefore, he may not have been aware of the things you speak of. These events are not publicised by the British government or the British media. I only found out about Britain's bad history for helping Jews fleeing from Hitler after I spent some time reading up on it.
Recently, a French pisher made a comment at a British party about Israel being a "sh*tty little country". The English press took it in stride. Right or wrong, it illustrates a mindset.
Because the British press have publicised stories about Palestinians who have been tortured or killed by the Israelis, then there is inevitably a feeling of suspicion/hostility towards the Israeli government. This can result in people letting anti-Israeli comments pass, but it doesn't mean the people allowing these comments to pass are anti-Israeli.
Given British history towards the Jews and current attitudes towards Israel, how should British reaction (or lack thereof) to these comments be interpreted?