Vehicle handlers who are employed by the French-owned firm STVA struck on Wednesday of last week over pay.
The 35 workers, members of the T&G union, are based at sites in Scotland, Birmingham and Oxford.
This was the third in a planned series of ten one-day strikes which are taking place every Monday.
Strikers were cheered when drivers from STVA subsidiary Car Commercial refused to cross the Scottish picket line in Bathgate because of health and safety concerns.
The workers do the highly responsible job of moving vehicles off train and truck transporters to compounds for onward journeys in Britain and overseas.
The handlers are campaigning for a pay increase from £7.05 an hour to £7.50.