I live in a semi circa 1860 in Maidstone, Kent. Just lately multiple cracks have appeared on the inside of the house, along both ground floor and first story ceilings and above the front door, back door and kitchen/lounge door above and about the doors together with some cracks in the plasterwork of the wall as a whole which consitutes the outside wall of the house. The outside wall is of a rough rag construction. I'm worried about the speed at which these are appearing and they have only just recently started. Could this be subsidence?
If it is happening quickly then you need to get it looked at. I deal with tree related subsidence in Kent and symptoms can take months if not years to develop into a significant problem. In the Maidstone area there are a numbers of underground features where voids occur, can' remember the name of the feature. One in Bearsted a while back and I recall seeing a report of one in the Boxley road are last week.