Removing lining paper before plastering

[Jimbo123]

In middle of a fairly major renovation project.
Contract with builder states…….
“- Doorway between hall and living room to be removed and made good each side with plaster”
And
“- To remove wall between living room and dining room, supply, and fit steel beam as to calculations on to engineering brick piers. Plaster and make good around the beam.”

This will leave three walls that require making good and skimming. 
The issue is the walls have painted lining paper on them and the builder wants ME to remove all the paper.
He states that the quote and contract was for plastering, not for removing the paper.

I expect him to ask for more money to remove the paper if I refuse.
He knew of the paper before the contract was drawn up as he commented that it needed to be removed before plastering.

Is this sharp practice or is it reasonable for him to behave like this ?

[jayc89]

Stripping paper isn't a builder's nor a plaster's job. When I'm getting my plasterer in I'd have the surface(s) prepped for him, ready to go, I assume he'd expect the same.

[markc]

I’m sure the plaster would do it but as an extra and do really want to pay traddies hourly rates for removing wall paper?