Plasterboard on tiles???

[Elliott]

Hi
We are redoing the bathroom and removed one layer of tiles to find another layer behind which is pulling off the original walling. To prevent extra work could we put plasterboard over these tiles and then plaster and paint? Will this be waterproof in a bathroom or do we have to go straight down to the wall - which by the looks of it will need a lot of work!
Please somebody help

 

[noseall]

rip the lot off, re-dab new plasterboards and fix aqua board to areas subject to frequent soakings.