Conservative Party Leadership Rules
If you thought Labour Rules for selecting leaders were bad, you're going to love these...

They really are dreadfully drafted but here's what I think they mean.
The key is Rule 3.
It's the duty of the 1922 to present a choice of candidates to the Party. The Party is defined (clause 1) as the Conservative and Unionist Party. And it shall consist of its members (clause 3). So, read naturally, the duty of the 1922 Committee is to give a choice of candidates to its members. This interpretation is rather supported by clause 10 (and the reference to "elected by the Party Members and Scottish Party Members").

And also the following words in Rule 3 ("selects candidates for submission for election"). And Rule 5 which makes it clear that the final choice rests with members.
The Rule 3 duty arises: "Upon the initiation of an election for the Leader." This language most naturally refers to the point at which a vacancy for party leader arises and the process for selecting a new leader starts. Read as such, the 1922 Committee has a duty to put two candidates before the Members. In a world in which there was only one nomination - or only one valid nomination - for Leader then rules 4 and 7 make clear you don't need an election. But we are not in that world. There were a number of nominations - and it was not suggested they were not valid.
Does the 1922 Committee (by Schedule 1 a Committee comprising all Conservative Members of Parliament) have power to change the Rules? Only if the Rules enable it to - and they don't (see Rule 90). The 1922 Committee has a limited power to set out the procedure for choosing candidates to submit for election to the members (see Rule 3). But it's pretty punchy to suggest this gives it power to ignore valid nominations given it has a duty to present to members a choice of candidates.
So what happens next? The safe thing to do would be to call for nominations again. It feels to me rather risky just opting for Michael Gove: who knows who Andrea Leadsom's supporters would have voted for without her in the contest? And if there are no nominations then we may well be able to enthrone Theresa May. But if there are, a choice would have to be put to members.
These are my thoughts. But do treat them with care. It's early days. If I change my view I'll say so here.
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Postscript. I understand that the Chairman of the 1922 Committee has stated that the leadership contest is over. He may have had in mind Rule 35 of the 1922 Committee procedure for Conservative leadership elections which provides:

but, if my analysis above is correct and I have seen nothing to cause me to change my view, this Rule is beyond such powers as are available to the 1922 Committee. But in practical terms it is, of course, a moot point whether anyone will challenge the Chairman's decision.