Wattle and daub (possibly)

Today I went to a meeting in Lancaster. I thought I'd be there until around 2pm but in the end I spent the most of the day there. In the afternoon we were up on the third floor of the old house which has now been converted into the client's offices.

As the meeting wound down, we got to talking about the old house and the chap I'd been working with, Andrew, offered to show me around. At one point, as we were going down a staircase at the back of the house, we encountered this 'window' set into the wall. It didn't look outside but, rather, allowed us to see the original wall.

Andrew said the wall - the bit behind the woven branches - was wattle and daub but I really don't know enough about old building materials to say whether he's right or not. Anyone have any idea?

Addendum. Please see the comment from MrsCH, below.