So, funny story. This is technically the first episode, but it's also the second one as it was recorded after the first one despite us watching the first one first and the second one second. Got that? Good.
All will become less clear once you start listening.
The key thing to note is this the Zygon Invasion episode, which should come before Zygon Inversion but doesn't here.
You can listen in the order we recorded, or the order of the episode – the choice is yours. We spoil you, don't we?