Bathrooms in Burton Latimer are more often about adding one than replacing one, because a lot of the estate housing has the space and only one bathroom in it.
Adding an en suite or a second bathroom raises three questions in order. Where the waste goes, since a new run needs a route to an existing stack with adequate fall and cannot cross a room at ceiling level without somebody noticing. What the floor is doing, because joists sized for a bedroom are being asked to carry a filled bath on a tiled floor. And what it does to the room it comes out of, because a bedroom cut below a usable size to gain an en suite is not always a good trade.
On the older terraces the soil stack runs externally and the layout options are narrower, so the drainage gets worked out before a suite is chosen rather than after.
Ventilation gets treated as an afterthought and causes years of trouble. An extractor discharging into a roof void puts the moisture straight back into the building rather than outside it.
Tanking is not optional on a walk in shower, because tiles and grout are not a waterproof layer and never were. Our bathroom installations page sets out what a full refit involves.