London Bridge closure 10/11 January 2015

Less well advertised than the changes from 12th January 2015 to London Bridge is that there are NO TRAINS via London Bridge platforms 1-6 on the weekend of 10th-11th January 2015:

From 01:10, Saturday 10 January 2015 to 04:00, Monday 12 January 2015., there are no train services calling at (in alphabetical order) DEPTFORD, GREENWICH, LONDON BRIDGE (platforms 1 to 6), LONDON CANNON STREET, LONDON CHARING CROSS, LONDON WATERLOO EAST, MAZE HILL OR WESTCOMBE PARK.

In general:
The Gillingham – Charing X semi-fasts via Woolwich Arsenal are diverting fast to Victoria after Lewisham
The Dartford – Cannon St stoppers via Woolwich Arsenal divert at Charlton via Blackheath and Lewisham then fast to Blackfriars
The Gravesend – Charing X via Sidcup services will terminate at New Cross, calling additionally at St Johns and Lewisham
It looks like the Dartford – Charing X via Bexleyheath services are cancelled, leaving the scheduled Victoria via Bexleyheath service.

Signalling Problems, London Bridge area, 2nd December 2014

There was particularly severe and long-lasting disruption in the afternoon and through most of the evening of 2nd December 2014, apparently centred on the section between London Bridge and Waterloo East.

The reason given was consistently “signalling problems”, but as this is apparently a catch-all that includes points failures and other infrastructure issues, does anyone know what the problem was ?