[mycroft]

If you say "it's obvious" and partner doesn't scream, you have an agreement. You may have never specifically discussed it, but you have one.

I know, it's hard to decide, and it's hard to not get caught by it. But there are those with 5 years and 1500 MPs worth of experience as partners who have a lot of scenarios where they have "no agreement" because they've "never discussed it" - deliberately (whether it's because they don't "have to" disclose it, or because it might not be legal, doesn't matter). And the regulators have to be able to deal with that.

[blackshoe]

There's hypotheses, and there's cases. With the hypothesis that an experienced pair may have an implicit agreement I agree. But the evidence in the OP does not support the idea that the hypothesis applies to this case.