P hil James, from Network Rail, said: "When the railroad was made of metal and moving parts, the sustained high temperatures took their place in places."
The Southern, Thameslink, Great Northern and Gatwick Express train operators initially said they would not compensate annual season ticket holders for Thursday's train delays unless they tried to travel, even though the company urged customers not to leave. After criticism, Govia Thameslink reversed her decision.
The Met Office said there had been about 5,000 lightning strikes on Thursday night, with a lot of gusts and hail reported as well.
