"Once elected, the job of an MP is to represent the people of his or her constituency (constituents) in Parliament, whether or not they voted for him or her."
Factsheet M1 Members Series Revised October 2005
I think the public would like the first job description to be true but believe that the second is more common. And that’s one of the reasons for a distrust of politicians.
(hat-tip to Bob Piper for pointing me towards the video but not for the reason of this post.)