I have replaced the fuse F6, the DPF Vaporiser, DPF Preasure Sensor and flushed the DPF with Cleaner and jet washed it thoroughly also checked the high preasure fuel pump . The car will still not do a regeneration. What am I missing or what else would stop it doing one?

Do you have the ability to read any errors codes? If you do what codes are given? Have you reset the 'dpf learned values'?

Yes, as above, you need FORScan and a decent lead to reset the codes and reset the DPF learnt values.

It will then regen as normal

No help to solving your problem, but how do you tell when the car is performing/has performed a regen?

I've owned my car for over 10 years and can tell by the change in engine tone/noise, also depending on conditions I can see the ash cloud coming out the back when booting it or sometimes just wafting out at steady speed.

If you've recently reset codes and it doesn't error again after many miles then it would usually have regen'd again. Resetting the DPF learned values could regen straight away (my experience when it was very full, in limp mode, and after a vaporiser change), or take more miles as it relearns....I have to do this now as the engine management light came on last night 🙄, have two round trip journeys to make tomorrow of 26 and 60 miles so that should be enough to relearn and trigger a regen...or it errors again! I swear the wet weather doesn't help the electrics (I get an open circuit error code so basically it doesn't fire up the glow plug in the vaporiser)

I'm not sure if it applies to your year, but i've heard on upto-2010 make, it won't do a regen if only one of the glowplugs is dead.