XF 2.2 D intermittent starting issue

On behalf of a work colleague.  

His 2.2 D will occasionally not start, tries it a little later and away it will go.  Been into the local dealership and they have diagnosed that the ignition switch is at fault, he's not too sure the exact part however he is on the cost, best part of £700.  Gulp.  He does not use it very often, lives local to work, so just short journeys.  As there are well known issues around the S-Type and their batteries I'm wondering if there could be a similar issue associated with the XF?  It's on 55k and I think a 2013 plate so the battery is some 5 years old, probably enough for a diesel on short stop/start use.  I've asked to check his battery volts as it has been standing for a couple of days and get back to me, guessing it should be around 12.6-12.7?

Anyone experienced similar issues.

Ta

Gary M