The cracks that concern me are:
running down the seam of the front room wall and the small bedroom (was once a large front room, split into a bedroom/front room a long time ago) between the outside and the partition wall (same crack) Plaster has cracked in a zigzag straight down. That seems new, rather than old crack re-emerging through the new paint.
Running down the seam between front room partition wall (supporting wall) and large bedroom (other side of front room to other crack). Again zigzag but much smaller. This is definitely not old, as this room has yet to be painted, But has probably been there a year? Another one on other side of the same bedroom, between bedroom and bathroom wall (the seam), quite big zigzag) and I think that one occured when the 'builder' lowered the ceiling and had the new floor resting on the old one, supporting by those supporting joist things (you know the ones that prop up ceilings?).
Very fine hairline crack running down the middle of the chimney breast in the front room - this may be an old one I never noticed but is now coming through the new paint. This has been there a while and does not appear to be getting bigger.
Very fine hair line crack running down the far end of the house right under the end of the main bulding (before the tenement of the house starts, and under the end of the loft converstion, on the big stair drop). Now this crack was always there, but I am not sure if this has got worse, it has come back through the new paint and has been there for a while, but it seems to go down further than it used to. Or it is more noticeable as the hallway is now white, and it used to be a dirty mustard colour (not my choice, already there when we moved!!). Also the plaster seems to have blown around the crack - this is an external wall between mine and next door neighbour, and the wall is solid, except when you tap it around the crack it sounds more hollow and looks a blown.
At the front of the house, outside, there is a crack above the front door, in the coving (is that the right word? ornate plaster edging around the door). This might, or might not have always been there. It looks dirty, suggesting it is old, but it is also quite deep. Not sure if this is significant or that is is simply the coving needing refreshing. A couple of other cracks like this. Might have always been there I just never noticed as the outside has always needed a freshen up.
It is an old house (c1890). Some of the cracks were definitely already there, some are new, some might have got a little worse. Some I have only just noticed but might have been there a while, some since conversion 18months ago.
I mostly feel this is ok, but there is a slight panic/sick feeling when I look at them, and I am about to call the builder who rescued us to come and take a look, see what he says.