Thanks for those suggestions. The hydraulic fluid level looks ok although it is very black. The Mondeo had a new steering rack and pump a couple of years ago so I would hope that they used clean fluid. They did make a mess of the job as it lost all the fluid a few days later whilst the car was in Scotland and my son drove back to the midlands with hardly any steering !
I'm now a big fan of electrically assisted steering (as on my Fiesta) as you can imagine !