Indeed, but a traditional MVHR would require ductwork which isn't common in the UK and often there isn't really any space to route it.

I have been investigating easier to retrofit decentralised MVHR systems such as the Prana Recuperator, Ventaxia Tempra and the Blauberg Vento. They can be noisy (not a problem for me, I don't mind noise) and quite expensive as you have to fit a number of units in different rooms, but still easier than retrofitting ducting.