Just a quick post on the above topic. My car recently threw a fault code for the handbrake, which led eventually to a total failure of one of the cables - the outer sheath managed to punch into the motor box itself after the plastic end of it failed.
Anyway, after much messing about I have had the system repaired by Blue Chip Autotronics near Usk in South Wales - Dave there is something of an expert on these systems having repaired hundreds of them.
He was able to refurbish the motor box with new motor, gearbox and relay, but the cables are unavailable for the Vel Satis at present. Esen SKV in Poland make them, but they are currently out of stock, and not likely to be available until July (if ever!) according to their customer services. Before contacting Blue Chip I had done some research online and took a chance on Renault Laguna 3 cables, the ones advertised as being 936mm and 1046mm in length, although they were actually slightly longer than that. These are 20mm longer overall than the originals, but the length of exposed bowden cable is similar to that of the Vel Satis. The units I bought had 40 and 41mm exposed bowden cable, while the originals had 39mm, but were so gnarled up that being completely accurate with the measurements was impossible.
I sent the unit and Laguna 3 cables to Dave and he refurbished it prior to fitting yesteday, and it all works perfectly. There were no issues with the small amount of extra length, although it has to be noted that the Laguna 3 cables do not come with locating grommets and these would need to be sourced, or removed from the originals. Likewise there is a length of rubber padding on the originals which is not present on the Laguna ones, but this was just substituted with a piece of rubber hose. Dave was able to test it on the car, and remove all the faults stored on the system.
So all in all a decent result, and cheaper than the quote from Renault - surprisingly the handbrake unit is still available as a special order but is £1200 plus fitting. Finally one advantage using the cables I sourced off eBay is that they have aluminium ends where they attach to the motor housing, so hopefully they will not crack and break again.
Regards, Steve