(there are pointers to this thread in England and Transportation sections of the Helpline)
Usually called off before they start, this time 2 big strikes will go ahead on London Underground very soon.
According to the official Transport for London website,
"Two 48 hour Tube strikes have been called for 4-6 February and 11-13 February. On Wednesday 5 and Thursday 6 February, some services are likely to operate between 7.00am and 11.00pm, with no services outside of those times."
For up to date updates see their page http://www.tfl.gov.uk/tfl/livetravelnews/realtime/tube/default.html
This is quite serious and there will be inconvenience around these strikes. If you will be in London during these times I suggest you check on updates.