alt Hacker NewsUS congressional districts being an order of magnitude larger than UK constituencies probably has something to do with it. Also, there are significantly more MPs than representatives, so you have to swing more legislators to your side in the UK vs the US to get your pet policies adopted.
(Sources: https://en.wikipedia.org/wiki/United_States_congressional_ap... , https://en.wikipedia.org/wiki/Constituencies_of_the_Parliame... )
But you can get a seat at the table for negotiations if the Tories are in power and you're a part of the Leaders group or the Treasury group of donors. All for £50k.
Leaders group puts you in touch with the Tory party leader (who is often the PM if the Tories are in power). Treasury group invites you to meetings with the Chancellor of the Exchequer.