Following Sweden's announcement last week that it will recognize Palestine, and in the wake of this summer's massacre in Gaza by the Israeli military and shifting public sentiment against Israel, UK parliamentarians from Left and Right stood up to heavy lobbying from supporters of Israel and either voted in favor of the resolution or abstained, which in itself was a demonstration of lack of support for Israel.
Part of the significance of the vote, which won't change Britain's policies immediately, will be the rush to downplay its significance by Israel backers, particularly the US media and the US government and US elected officials. It's also significant because it was the "Balfour Declaration", during the time after WWI when the UK was in control of Palestine, that set in motion the process of taking half of Palestine away from its inhabitants for the creation of a Jewish state.
Primarily though, in my view, it marks the fact that the US was unable to keep a major ally in line and adhering to it own official policy, which is to refuse to talk about Palestinian statehood outside the context of "direct negotiations between the two parties," i.e. Israel and Palestine.
That farcical policy has been used for decades as cover to allow for the continued theft of Palestinian land through "settlement" building, and increasingly shows signs of unraveling.