Cheers @branwen it's a Bob Jackson Vigorelli with 25mm tyres used on the road.
New plan! I've got work tomorrow, that's a 10 mile ride each way. I'll ride one saddle there and the other on the way back. Whatever feels best will come with me on the Audax. If it gets unbearable after 180k when I pass my house I'll pop in and swap them over, if not I guess I've found a saddle that's fine.