[dvboy]

Countryfile is airing as planned at the minute for the vast majority of the country. In this particular instance it would probably make sense for the Tennis to move to the red button and IPlayer for viewers in wales at 21:00 so that Countryfile and the News can be aired (With antiques road show being a repeat the value in this being broadcast is significantly lower than is the case for the other programmes).

That won't happen because a) Today at Wimbledon won't get onto iPlayer and b) they have already committed on air to showing the tennis on BBC Two through the evening to its conclusion.
I think it's likely BBC Wales will get a bespoke bulletin at 23:00 on BBC Two and then they'll show Today at Wimbledon at 23:30. They'll have to find another slot for Countryfile in Wales or give up on it - continuity on BBC Two Wales at 20:00 said it would be available on iPlayer at 21:00.