We were having trouble with a cross over, it was the same part but constructed differently, so it fitted into the gap correctly, but the sleepers were in the wrong place.
When i left, Salisbury and Southampton had just arrived to begin moving the sleepers, they have the road until 16:30, so should get it done in time, just depends on the welders.
They were having trouble with a Virgin somewhere last night before the block went down, maybe a unit ended up the wrong side of the block hence the delay.