In pics: Strikes cripple UK railways for second day as unions warn of more to come

Only around a fifth of services are set to operate on heavily reduced hours, with those still running starting much later in the morning than usual and set to end as early as 6:30 pm.

A third day of strikes is planned for Saturday, with fears of further walkouts in the weeks to come.

With Britain suffering from rocketing inflation and stagnant economic growth, the industrial action which could be mirrored by workers in other sectors over the summer has echoes of the 1970s.

Then, the country was crippled by a wave of strikes across various industries while struggling with rampant price rises and non-existent growth, a toxic combination known as stagflation.

Railway bosses, backed by the government, argue the system costs far more to run than it generates in revenues and needs to modernise through greater flexibility over staff numbers as well as pay.

Steve Montgomery, who chairs the Rail Delivery Group, which represents various operators of train services, said reforms should still "accommodate everybody who wants to stay within the organisation".

Prime Minister Boris Johnson, who is attending a Commonwealth summit in Rwanda, criticised the strikes as "unnecessary" and urged what he called "union barons" to accept "sensible reforms".

"I think people should get around the table and sort it out," he added, despite criticism from unions that the Conservative government should be present at negotiations as the main funder of the network.

People hoping to make it to the Glastonbury music festival in southwest England were among those impacted by Thursday's strike, with far fewer trains than usual to the nearest station in the region.

Location technology firm TomTom reported road congestion at 9 am was higher than the same time last week in and around the British capital and the northern English city Manchester.