So, funny story. This is technically the second episode, but it's also the first one as it was recorded before the first one despite us watching the first one first. Got that? Good.
All will become less clear once you start listening.
The key thing to note is this the Zygon Inversion episode, which should come after Zygon Invasion 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?