Taffy, For what it's worth and you will already know some of this. If you are looking at steering pump failure the following is of interest. The problem was identified early in production, in our Mog club one to 1st Aero's in 2002 had pump failure early, I believe in the 1st year . It had to be recovered from France to the factory. They used a later Mini pump and not the Rover version put in at build. The series 2 had this upgrade as standard.
I spoke with Richard Thornes service team about it and their solution on a car they fixed this year. It started with sourcing a pump, these are circa £500 BMW Mini, 06 version, I believe. High pressure hoses were required and made by Pirtec, as well as some seals. Finally they sourced the electrics out to a local firm.
Not sure with simonrjw's job whether all this was needed but Simon at SIFAB was hoping to have a packaged solution for all of this, plus written instructions
Here's hoping your job is not as serious but it is worth knowing someone has solved the worse case.
A packaged solution would be great, especially if it stays hydraulic.
I do not think the RT fix is worth pursuing, it costs an absolute fortune and is electric so I would imagine this results in reduced steering feel..