General secretary of the Public and Commercial Services (PCS) Union, Mark Serwotka, reportedly said Number 10 could face "post-strike action litigation" over its airport contingency measures.
Around 1,000 Border Force officials at six major UK airports embarked on their second four-day walkout over the festive season on Wednesday (28 December), but there were few delays due to military personnel and civil servants being deployed to cover the striking workers.
According to The Telegraph, passengers passed through immigration in "just a few minutes" at Heathrow, which was expected to have faced the worst disruption.
A Heathrow spokesman reportedly said: "Operations continue to run smoothly and the airport is operating as normal. The immigration halls are free-flowing with Border Force with the military contingency providing a good level of service for arriving passengers."
Serwotka claimed the government was able to avoid delays by using hundreds of military personnel from the Army, Navy and Royal Air Force – who he said had no authority.
Speaking to BBC Radio 4’s World at One, he said: "The price the government is paying to not have queues is that they are not discharging their legal responsibilities.
"Staff are being brought in at huge expense from all over the country to offer a fraction of the service that our striking members would normally be offering. I suspect we may well see some post-strike action litigation around this question."
