Rail commuters endured rush-hour travel misery for the third day running today.
A series of problems led to hold-ups and some cancellations on a number of busy lines, including the Gatwick Express.
There were also delays at two major rail junctions - at Clapham in south London and at Watford in Hertfordshire.
At Clapham, a signalling problem caused delays to Gatwick Express trains and to services run by the Southern train company.
At Watford, the difficulties were caused by overhead wire problems which were affecting trains run by London Midland which was also experiencing - again - train driver shortages.
The Watford problems were hitting services run by Southern, Virgin Trains and ScotRail. Virgin had to axe some services between London and Birmingham and Manchester.
Southeastern services were affected by a broken-down train at Bexleyheath in south east London, while emergency engineering work at Motspur Park in south west London led to delays for passengers with South West Trains.
Another signalling problem - at Earlswood in Surrey - led to delays between Gatwick Airport station and East Croydon in south east London, while signal difficulties between Angmering and Ford in Sussex meant hold-ups for passengers with the Southern and First Great Western (FGW) companies.
There were delays between Prees and Wrenbury in Shropshire due to a broken-down train and this caused delays to Arriva Trains Wales services between Shrewsbury and Crewe, while a train derailment between Mirfield and Wakefield Kirkgate in Yorkshire led to buses having to replace trains on some routes in the county.
A landslip near Bristol earlier in the week was still causing problems today, with delays to FGW services between Bristol Parkway station and Swindon.