Central transmitted it first, and other stations used their edits. So quite possibly they sourced tapes from Central as the dispute progressed. They would have been behind Thames but may have scheduled a few extra episodes to catch up.
A few Thames programmes were shown in London only, such as Up the Elephant and The Bill. Other regions saw these episodes later - I remember a viewer querying continuity in the Bill when a character was seen driving a car they had sold months earlier. The response from ITV was that three episodes were shown in London only, and were tacked onto the end of the series in other regions.
Thames scheduled Coronation Street four times a week for a while after the strike to catch up - I remember their subtitles appearing on Oracle P399 (the local pages) as subtitles for the wrong episode were going out on P199. This was the year before P888 became the standard subtitles page across all channels.
I notice commercials went out in London - a special arrangement must have been in place to sell these as the advertisers would have paid for slots in advance around the usual schedule that obviously didn't appear.
I'm not sure if Thames were able to insert adverts onto Channel Four. There is certainly footage from this era showing break filler captions going out on Four - this may or not have been for the entirety of the Thames dispute.
CEEFAX SUBTITLES BEGIN SHORTLY