Updated info from national rail
"Arriva Trains Wales
A 50 mph speed restriction will be imposed at a number of locations in Wales, resulting in possible delays to trains of up to 15 minutes. Arriva Trains Wales services will also be temporarily suspended between Wolverhampton and Birmingham International - the last service out of Birmingham will be the 09:10 Birmingham International to Holyhead, and services will resume with the 11:27 Holyhead to Birmingham (New Street only).
Gatwick Express, Southern and Thameslink
Due to unusually high winds, widespread speed restrictions have had to be imposed for safety reasons due to the likelihood of line obstructions being encountered. Disruption to train services is expected from 07:00 onwards, and may increase in severity throughout the day.
Customers should see the Alternative Routes posters here for Southern and Thameslink, or at the station, for more information on how to complete your journey should your service be affected. Please be aware that buses have a limited capacity and you may not be able to board the first available bus.
Virgin Trains
Virgin Trains plan to run a full timetable on Thursday 23 February. But speed restrictions mean it is possible journeys might take longer than usual. If customers want to change their journey, tickets for travel tomorrow can either be used for the rest of today, or on Friday providing you begin your journey before 14:00."
http://www.nationalrail.co.uk/service_disruptions/today.aspx