The actress praised former co-star Rob James-Collier, who plays Thomas on the ITV period drama.
She told PA: "I watched the first series but I never watched the second one as I just couldn't catch it regularly because of my new baby.
"I've bought it on DVD so I intend to watch that, I loved the first series so much that I have to see the second one.
"It's a far cry from playing Liam! I think he's done a great job and we're all very proud of him."
Marsh, who plays Michelle Connor on Coronation Street, added: "I'd love to do a period drama. I'd love to be in Downton Abbey, it would be amazing. I don't think they'd bring me in as well, though!
"I'd have to play a maid, though, I wouldn't be one of the posh ones, I'd definitely be a maid. It's always nice to do different things and dress up, it's like playing dress up as an actor."
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