Temperatures soar in the height of summer, warping iron tracks and delaying trains. Problems are also caused by trespassers on the line, suspect drug users and an electrocuted pigeon.

The staff step back in time when they venture down into tunnels under the station to carry out fire safety checks, and it is the start of the Bank Holiday getaway for thousands of commuters. Jennie, Great Western Railway's new customer ambassador, manages to seat a troupe of young cheerleaders all together, but faces a much bigger challenge when fire alarms go off during rush hour.

Signal problems lead to a restricted service during rush hour, which causes severe congestion at the station and the same equipment causes more grief 24 hours later - leading to the complete suspension of the line. Jonny and his team of engineers are replacing a 60ft section of rail as one of the clamps holding it in place has weakened, but they have just four hours to complete the complex task before the morning rush begins.

The Queen arrives at Paddington on board one of GWR's new Intercity Express Trains, commemorating a trip made by her forebear Queen Victoria. At Reading station, Revenue Protection Officer Lyn has to call for back up when a fare dodger makes a run for it.

A driver raises the alarm when he suspects that his train has hit something - or someone - on the line, while heavy rain brings down a tree which closes the tracks between Banbury and Oxford. Plus, engineers begin the process of dismantling a Victorian viaduct.

Sunday's service grinds to a halt when a train de-rails in the station, a knife-carrying passenger causes concern in Bristol, and cleaners have to respond as passengers ignore the 'Do not flush while in a station' signs.

Transport Police are called after a passenger urinates in a carriage on a train pulling into the station, a low bridge has to be assessed after it is hit by van, and a train's brakes fail in Reading causing widespread delays.