telephone ta flavel and sons, stockton, (name and no in a google search) it is a diesel specialist. they actually make by hand, TWO non return valves which iliminate cold start problems. can be fixed for about 20 quid. but you will need both, its no good just putting one in
if not any of the other suggestions it may be the injector seals (easy to check just look in the fuel filter, if it has oil in it then its the injector seals or it could be the glow plug relay or fuel filter tops are well known to cause problems
and if not any of the above put it on a computer as it could be the fuel pump
i hate diesels, March 2009