I just had a quick look at Zoopla. From what I can see, they have:-
Painted the exterior of the house and put new external lights by the front door. They have also replaced the back door.
They have added some secondary double glazing to the back of the house.
Replaced the flooring on the ground floor with engineered wood and the carpet on the stairs. It's a bit of a shame they did that really as it used to have the original floorboards which appeared to be in very good condition. But I know that's not to everyone's tastes.
Other than the flooring and painting the living room walls they haven't touched the ground floor internally, the kitchen and the wood burning stove were already there when they bought it.
Upstairs they have replaced the very old bathroom, however, they have removed the bath and there is now just a large walk in shower. Feelings are often divided about not having an actual bath. They have also painted all the walls.
They haven't done any work on the garden except to cut the grass. The small retaining wall in the back garden was already there.
Frankly, having now looked at the previous listing, I don't think they've done anything beyond the normal sort of cosmetic updates. The major expenditure they had was putting in a new bathroom (which was really needed) and also putting in engineered wood flooring which is just a personal choice - the original floorboards and kitchen floor looked fine.
Personally, I don't see where that represents an extra £46k in value.