Chancery Lane unit

Is there any official definition of which FGW services are "high speed"? I was at BTM yesterday when a service to Taunton was advertised as such - formed of 1 Class 143 unit calling at all stations, includign Parson Street and Weston Milton!
If this is a high speed service, then what isn't?

Also, there was a couple of occasions when passengers at platform 8 were told there was a train passing that wasn't due to stop, followed by a train passing through the station along the centre road between platforms 3/4 and 5/6. On at least one occasion there was a stationary train on paltform 7.

Passengers at platform 10 were similarly advised, but then the train (a Portsmouth-Cardiff or vice versa) stopped at platform 9 before reversing out northbound.

Firstly yes, to the passengers the stand clear announcements do seem confusing especially when there is a train stood in the adjacent platform. The reason for this is due to the CIS (Customer Information System) works on headcodes, by this I mean when a train departs from the station and passes the signal, it autoamtically deletes that train off the screen. This can only be done if the
train is carrying the correct headcode. If a train is stood on Platform 7 (lets say for example) then the headcode of that train
will remain on the train describer system on platform 7. So anyway if say for example a Cardiff train gets routed into 7 on top of the
stationary unit then what happens is that previous headcode of the stationary train will get pushed automatically into Platform 8 so by this the auto announcing system will announce stand clear because it doesnt recognise that headcode that has been pushed into Platform 8.
After which Digital Doris as we call her at BTM will then announce the Cardiff train arriving on 7. So whatever passed through the through roads wouldve had no affect whatsoever on the platform announcents.

It all sounds a bit complex I know! Its the same if any freight train or empty coaching stock trains pass through the platform,
Digital Doris will announce these as stand clear because the CIS only recognises Class 1 and 2 trains, a problem we are encountering at the moment with VXC's 2 Class 9 trains that stop at BTM, 9S66 on the up and 9V61 on the down. The system doesnt recognise Class 9 so we have to make sure they are announced manually or else she'll announce stand clear and no b*gger will get on it!

With the 'high speed' thing, yes I have noticed this week that some of the local services have been announced as such, this I can only guess were entered into the system in error. It is only supposed to announce the HSTs and 180s as 'High Speed' but hey it does create a small source of amusment when she annoucnes as 'high speed' and then a 143 comes around the corner!!