I removed mouldy wallpaper to find this - any guidance appreciated

[Rupert22]

Hello.

The lower part of these external walls were mouldy, so I removed the wallpaper to find this.

You can see from where I've opened up a small hole, that the render is straight onto brick (Victorian, solid wall, but cement render on the exterior).

The lower part of the walls have mostly been re-finished in something grey & quite hard - any idea what this is? Could it be Gypsum based & exacerbating the damp/mould?

I'm assuming the original finish was sand/lime, is that right?

There's areas which look like they've been repaired/blended with modern plaster, but it's all a bit pink, so I'm pretty confused and definitely not sure what the best thing to do now is - I was supposed to be decorating!

If anyone can offer clear insight, I'm all ears.

Rupert.

 

[Rupert22]

Here's some photos showing more of the area, in case that helps.

 

[Monkey Boy]

Was the heating on sufficiently for starters? Was the occupant elderly and skint and turned heating off? Was the area ever flooded?
I’m sorry to say but if you want it all nice you have a case of an old house that needs some thoughtful renovation and it isn’t a 5 minute cheap budget job.
You should to get people in who know what to do if you can

 

[Rupert22]

Was the heating on sufficiently for starters? Was the occupant elderly and skint and turned heating off? Was the area ever flooded?
I’m sorry to say but if you want it all nice you have a case of an old house that needs some thoughtful renovation and it isn’t a 5 minute cheap budget job.
You should to get people in who know what to do if you can.

Thanks for replying @Monkey Boy.

The house is a rental & belongs to a neighbour's brother. The tenant moved out & my neighbour asked for my help painting, as I'm a lot more practical & experienced than him. As you can see though, it's got a bit out of hand!

I haven't been in the property when it was inhabited, so I can't comment on how well it was heated, but I do know there was a family in there, which meant this room wasn't being used as a living room as intended, but a second bedroom.
There's a remarkable number of louvered air bricks around the place, which look like they've been in place for decades, so it's certainly been ventilated. The hole in the photo is a vent, but apparently that was added in recent years.

The mould was mainly on the grey area, which makes me suspicious of what material that is & why it's there.

 

[Rupert22]

I sacked off the plaster repair option and am using lining paper instead, with Wallrock thermal liner on the external walls.

 

[Cockney]

I sacked off the plaster repair option and am using lining paper instead, with Wallrock thermal liner on the external walls.

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