What is rather annoying about all these 'revelations' is that I was involved in the early consultation exercises for the DH. The initial estimated figure to get the properties to the decent standard was around £50B (based on the local authorities surveys), this was then watered down to about £20B with the view to reduce that figure even further. It was no longer DH and I then decided to jump ship.
The main concerns/warnings voiced at the time were the time- table to complete the works were unrealistic and the quality of the work will be sub standard because there weren't sufficient quality trade or resources to embark to on such a large scale operation.
Clearly the mandarins chose ignore all that because they wanted to please their political masters and they of course wanted quick fixes!