Bluebulb Projects' The Measure of Things presents:
850 is about one-and-three-tenths times the number of Members of Parliament (The U.K.).
In other words, the count of Members of Parliament (The U.K.) is 0.770 times that amount.
(a.k.a. MPs) (2016 figures) (formally "Members of the House of Commons of the Parliament of the United Kingdom of Great Britain and Northern Ireland")