blown plaster ( original plaster ) . I have pulled all wallpaper off plaster fell off in places back to brick . So I have removed most of the loose plaster . Today the electric bloke chased the walls and said plaster is crumbling would I be better off asking the plasterer to take every wall back to brick & start again or do I ask for it to be patched
Not saying this to be an insensitive arsehole, just saying it to give you an honest opinion:
If you patch the walls, it might last a few years more, but you're likely to experience cracks (both in the remaining old plaster and along the joins between old and new portions). You're also not going to be able to prevent the old plaster from continuing to gradually seperate from the brickwork.
If you go on youtube, you are likely to encounter videos of people embedding big sheets of render mesh (fibreglass mesh purchased in big rolls like wallpaper) into a layer of plaster that they're applying onto a cracked old plaster wall. The idea is that the render mesh will reinforce the new layer of plaster to make it less likely to crack, if the underlying old plaster degrades further. Please understand that this is not a 'proper' solution - it's a bit of a bodge, since the underlying old plaster is likely to continue to gradually seperate (blow) from the brickwork, over time, and eventually, because of the fibreglass render mesh holding everything as one, the whole bloody lot may start to come off the wall, in big sheets. Therefore, although it can be done, it's not a good idea.
So, the truthful answer (in my opinion) is that you should really bite the bullet and hack everything back to brick, to have it properly plastered.
As you can imagine, this won't be cheap, but how long do you intend to live in this house? If it's more than 5 years, it may be best to bite the bullet and pay to have it done properly.
What you have described is
extremely common in Victorian / Edwardian houses. Some plasterers may advise you that they can happily skim over the top of dodgy old plaster, but then some mechanics have happily sold remoulded or part-worn tyres to car owners for decades, and they're now pretty-much banned, with good reason.
Ultimately, the decision is yours, and I can appreciate that money may be a major consideration. If you literally cannot afford to pay a plasterer to plaster from bare brickwork, then so be it, but if you're on the fence, and can just about afford to have it done properly, and plan to live in the property for many years, then you now know that the best course of action would be to hack it all back to brick and start fresh.
Lastly, please don't make the mistake of relying on 'reviews' of plasterers on sites like checkatrade, trustatrader, etc. There are some good tradespeople advertising there, but there are also far too many chancers playing the system to take naive people's money, unfortunately.