They literally got the job thanks to a campaign were Israel-linked Jewish Associations in the UK helped them demonize the previous leader of their party as an anti-semite to get them to leave, a slander campaign which include amongst other things calling a Jewish Holocaust Survivor an anti-semite for what he said about Israel in a conference for Palestine as a way to taint said party leader by association (as we was sitting in the same panel).
Britain having a First Past The Post system like the US and these two being in one of the two parties of the power duopoly created by such as system, being given the party leadership meant that in due time they would be in government.
Israel bought these two with power, at the very least, whether money too or not is unclear, and given that the part of the British Justice System that deals with Corruption is seriously disfunctional (curiously, amongst other things the faction of the party to which these two belong kept reducing funding in real terms for the sole Judicial entity that deals with Fraud and Corruption - the Serious Fraud Office - during their time in government previously), so we'll never know since if they actually are corrupt it will never be investigated, much less prossecuted and a conviction secured.