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Brick or block walls will have something underneath them to support them. Traditionally this would be another wall constructed out of brickwork / blockwork but it is often the case these days when people want to open up the ground floor of an older property that the wall on the ground floor will be removed and the upper part of the wall will be supported by structural steel. 100% this needs to be signed off by a struc. eng. as well as building control your solicitor should request any certification from the vendor. However I would be astounded if it wasn't picked up by a surveyor and even if they hadn't picked it up there would be a cascade of professional indemnity insurance to cover you.
If the wall on the first floor is a stud wall then you will be ok.
Sorry, just coming back to this comment. Thinking about it there is a wall on the first floor pretty near and possibly above where the removed wall was. What does this suggest?