From a Facebook post on the
UK▸ HST▸ Enthusiast Group page:
6th September, Exeter to Penzance, if all goes to plan, first 2+4 HST with sliding doors and CET▸ toilets enters service.
All but eight of the 24 power cars being converted are known. The twelve First Group owned examples plus 12 Angel owned. Four of the Angel ones are already painted in green, they are staying.
11 sets being converted with 4 spare vehicles. Eight diagrams a day on the Exeter-Penzance and Cardiff-Taunton/Exeter axis once all are in service.
So 2nd September OC Open Day, 6th September, HST second life begins. Could be a very interesting month.
Whilst this isn't from an official source, I've no reason to disbelieve it. One set of Mk3s with CE toilets and power doors is nearing completion, and two Class 43 power cars have already been modified for operation with power door Mk3s. More converted HST sets will come on stream as the first few Class 800/0s enter passenger service from this summer.