Thanks to all for your support and apologies for not posting sooner (I forgot!)
The new in tank pump cured the non-starting, although I was not able to replace it without completely removing the tank first.Typically, the customer had just filled up and I had to drain the tank fully before removal.

Strange though that during the initial attempt to get it going it flagged up SOOT FILTER BLOCKED on the dash.I didn't pay too much attention to it whilst it wasn't going due to flat battery etc but once the new pump was fitted and working I checked the codes and DPF code wouldn't clear.Road testing put it in limp mode and extended motorway road test made no difference.Customer said there were no DPF issues before breakdown.

Back at the shop the DPF pressure readings looked odd but after a new pressure sensor and another motorway blast the DPF regenerated , the codes cleared and all was good.

Sorry this last bit is not very scientific and I didn't keep the codes but it was three weeks ago and to be honest I was glad to see the back of it.
Colin.