The Political Review Commission in 1998 made this recommendation:
“The Prime Minister and Ministers to be paid their present salary and allowances incorporated into a taxable package as recommended in the Report of the Civil List Review Committee of 7 November 1997; to devote their full time to ministerial responsibilities, and not to engage in other income-earning occupations.
“The work of ordinary Members of Parliament to be regarded as a part-time occupation.”
Since that time the population has decreased, as has the number of days Parliament sits, and therefore, the amount of work MPs do.
It’s hard to justify the massive pay rise.