Phil 'the windmill' Avery highlighted some model differences between the UKMO and the ECMWF for midday Thursday on this lunchtime's weather forecast (1.57 PM).
He then rather oddly went onto show the forecast graphic (ECMWF?) which shows no thunderstorms across central areas at midday.
Here are some of the other models...
This is how the UKMO see midday on Thursday (afternoon video forecast), and as you can see they already have heavy showers breaking out from Devon to Sussex, so I'm not at all clear what Phil Avery is going on about.