By what process did it come about that 100 nominations are now required for the Conservative leadership election in October '22

Question

In elections there is normally a set of rules for running the election and those rules are either consistent from vote to vote, or there is a clear process for changing the rules.

In the summer of 2022, the Conservative party held a leadership election. One of the rules was that "candidates needed the nominations of 20 Conservative MPs" (source) to enter the first round, and 30 votes to proceed to the second. (This was apparently to rapidly eliminate candidates with very little support in the Parliamentary party.

In October, in a second leadership election, 100 nominations are required, a substantial barrier which may well result in only one candidate and a "coronation". It may eliminate the party membership from a role in the selection of a leader. (source) Had the July election been run under October rules, there would have been no candidates at all!

By comparison, in 2019, only 8 nominating MPs were required.

How was the rule changed? How much could the rules governing the election of a leader be changed?

Answer 1

The house of commons library confirms this as essentially unanswerable. As posted in a comment it is not clear that the rules have been changed. At each leadership election the head of the 1922 committee announces a threshold of support required for candidates to be placed on the ballot of MPs. How that threshold is determined is an internal matter.

Commons Library

The rules and procedures for stage 1 of a leadership election are determined by the Executive of the 1922 Committee in consultation with the Conservative Party Board. This will include how an MP can be validly nominated.

The rules are not in a publicly available document. Each time a leadership election is held the chair of the 1922 Committee will announce the rules to be followed and the timetable.

So it appears Graham Brady simply announces the level he wants and it is within his gift to pick any number.

"We fixed a high threshold but a threshold that should be achievable by any serious candidate who has a prospect of going through," Sir Graham said.

As for why a high level has been chosen this time, that would require speculation on internal motivations,but given the desire to have a replacement in place quickly a small field is probably required.

Sir Graham has already said that the new prime minister will be chosen by Friday 28 October, with Ms Truss to stay on as PM until then.

The 28th is 8 days after Truss resigned, last time round resignation to being reduced to two for membership vote took 13 days.

Timeline Red line is Johnson's resignation, the yellows elimination of various candidates.

Answer 2

Further to @Jontia's answer, the whole process flows from this clause in Schedule 2 to the Conservative Party Constitution:

Upon the initiation of an election for the Leader, it shall be the duty of the 1922 Committee to present to the Party, as soon as reasonably practicable, a choice of candidates for election as Leader. The rules for deciding the procedure by which the 1922 Committee selects candidates for submission for election shall be determined by the Executive Committee of the 1922 Committee after consultation of the Board.

Here, "The 1922 Committee" consists of all Conservative MPs who do not hold ministerial positions; "The Party" means the wider party membership beyond Parliament; and the small group of people standing around Graham Brady when he announced the hundred-nominations threshold were the other members of "The Executive Committee of the 1922 Committee" plus one representative of "The Board" (Jake Berry).