“The UK Border Agency is aware that the visas of some Libyans may expire before they are able to leave the UK, due to the current situation in Libya. Travellers transiting through Libya to other countries may also be affected. The agency appreciates that this is due to exceptional circumstances.
You should keep proof of original travel plans as evidence of your intention to comply with your visa requirements. You should make arrangements to leave the country as soon as possible.”
See here for original. Doesn’t seem terribly realistic to me. One would have thought the least we could do is tell them they won’t get into trouble for overstaying. It is possible to read that between the lines here but it requires a bit too much imagination on the part of the reader, frankly.