Just been into the local dealer to do a quick check on financials.
you can get 3.9%apr on any F30 diesel until at least the end of the month, although he thought this would probaly run into next month.
Most I could talk him down from list price on a fairly low spec 330d M Sport was 4%. Which would give me a deal on 48mnths of ~£550pcm based on deposit, mileage, etc.
Could negotiate more off a 320d M Sport, about 7-8% which may be workable for me. Even so, you can see why people are attracted to 3rd party lease deals when you can get a basic 330d M Sport on a 2yr deal for under £350pcm.