Thameslink trains has warned of possible delays and cancellations after a late train driver caused a halt on the northbound express line.

The 6.20am Three Bridges to Bedford service was lacking a train driver, which blocked the fast line for 29 minutes and caused a buildup of trains by around 8am.

The line has now reopened, but passengers are warned there may still be disruption between Luton and St Pancras up to 10am, including possible delays and cancellations.