Makes a change from the crampt three car class 158's. Wouldn't one diagram (whether that's be Cardiff to Portsmouth or Westbury to Worcester / Great Malvern) be operated with a 166 come the 3rd February when a 150 is sent North?
The 12th February date is misleading. GWR LTP planners work on fixed period dates only but the cascade plan works on intermediate dates so any of those changes have to be done via STP rather than LTP.
12th February is the start of an LTP fixed period date but it is on the 29th January that Weymouth should see the first Turbos in passenger traffic when two more diagrams cut over to Turbos, the first ones involving use of the modified door controls for use on short platforms. The following week 7 cl 150/1 units should head north.
Then on 12/02/18 further diagrams should cut over, the situation being as per the 12/02/18 LTP diagrams. The next Turbo diagram to be introduced after that is currently scheduled to be on 26/02/18.