Has more to do with where the industrial centres of the 19th century were within a city and how cities have evolved and developed over time, making those centres prime residential zones now. In Bath's case there is a clear need for more housing in the centre with massive objections from residents to the development of greenfield sites on the outskirts of the city.
Sites like these are politically 'easy' to develop. From a urban landscape point of view, taking an industrial zone and re-classifying it as a residential zone has it's risks in that you drive out the ability for employment opportunities in the city. However, in Bath's case, the industrial sectors are now on the west side of the city towards Bristol.
I lived there for a few months. The structures are extremely sturdy, with some fantastic views from the upper levels. The base of the Gasometers have been cleverly fashioned into a shopping complex, with adjacent cinema and gym. No need to ever venture outside! (Even the underground train station can be reached under cover.)
My apartment overlooked one of the hollow central 'cylinders': not much sunlight reached the interior, and - without net curtains - not much privacy (since neighbors opposite had a clear view across the space).
After seeing a huge crowd queuing in the lobby one evening, I realized the basement was used for rock concerts! And yet, not a sound (or vibration) reached the residential areas above.
The gasometers in Bath were in the middle of a pretty substantial industrial complex, and the land is substantially contaminated - but apparently a few feet of turf is "good enough".
Sites like these are politically 'easy' to develop. From a urban landscape point of view, taking an industrial zone and re-classifying it as a residential zone has it's risks in that you drive out the ability for employment opportunities in the city. However, in Bath's case, the industrial sectors are now on the west side of the city towards Bristol.