This is a weird one...

My accelerator pedal lacks progression and the turbo is kicking in too late. For the first 30% of travel or so I get a decent amount of power, but when I demand more power right through to the pedal stop there is no change in the rate of acceleration. The turbo feels like its spooling up too late as well because it kicks in at around 2500rpm.

This issue is most apparent in 3rd, 4th and in-gear acceleration at 5th is slower than it used to be. I can't hear any boost pressure being lost either so I have no idea what's causing it.

It's a 1.6tdci (DV6) engine.

Could it be in Limp home mode, sounds like a good description of how it feels

Can you rev over 3000 rpm?

Yeah the car revs over 3000rpm perfectly fine. On the motorway the car also appears to be fine to the point where I've barely got my foot on the accelerator to maintain let's say 70mph or so, but just seems like it's a little slow in picking up the speed compared to 12,500 miles ago.