Most of us have an employment contract that specifies that we have one job only. MPs should have the same experience as those they represent in order to be able to represent us. If being an MP is a full-time job, then they should work at it full-time. If being an MP is not a full-time role, then clearly we need fewer MPs so that it is a full-time job for each and every one of them.

Additional paid work exposes MPs to allegation of corruption or sleaze, so being obliged to do one paid job only protects them from this. Some MPS claim that additional paid work gives them expertise and insights into particular sectors or concerns. If this is genuinely the case, then they will surely be happy to do this on a voluntary basis, just as many of their constituents volunteer to become school governors, for example. 

Another argument that has been presented is that MPs' salaries alone won't attract the 'best' candidates. MPs' salary is currently £81,932. Anyone who can't live on this salary is clearly unable to represent constituents living on the average weekly earnings for total pay of £581 (ONS August 2021).