I've always noticed that Britain seems to have a much less prominent Jewish community than mainland Europe. We (historically) don't seem to do "ghettos" or have a history of rampant anti-Semitism.. but there are small communities here and there despite a 12th Century expulsion... I always assumed these communities were formed out of WW2 refugees... But a Wikipedia article I just read suggests the population went from about 40,000 in 1880 to more than double by 1890 ... A good 50 years earlier than I would expect.
What was going on in the world at that time to encourage so many Jews to move to Britain in such a small space of time?
Many Jews in Russia started fleeing the pogroms that started in 1881. Try reading "Russians, Jews and the Pogroms of 1881-1882" by John Klier. For another text that is accessible on line try this travelled to the US but at the same time many went to the UK building communities in the East End of London, Hull, Leeds, Bradford, Manchester and Liverpool. Note that with Disraeli becoming Prime Minister, although a converted jew, the country had become more tolerant.
There is a popular story that many went first to Hull and were traveling towards Liverpool to get to America but settled on the way via chain migration. I can't find any real source for this but as the cities are almost in a line across the country, it is an interesting thought. Btw, Leeds, Bradford and Manchester were heavily industrialising at the time (textile industry) so there would have been work.
As said in the other comment, it's for the same reason that the American Jewish community boomed at the same time- starting after the assassination of Tsar Alexander II in Russia, which was (falsely) attributed to the Jewish nation by many, there was a wave of pogroms from 1881-1884 in the Pale of Settlement, where the Russian Jewish population lived. In fact, an advisor to Tsar Alexander III later said that he wanted 1/3 of Jews to convert to Christianity, 1/3 to emigrate and 1/3 to be killed. Jews had serious motivation to leave, and many did.
Some Jews would have decided straight up to go to England, but America had a unique reputation- people were writing home about how it was "the goldeneh medina" where the streets were paved with gold, and so people specifically wanted to go there. But the boats often left to America from England, and it wasn't uncommon that some Jews would have enough money to make it to England, settle there "temporarily," and then end up staying put.