Chris Plastow
This is a tricky one . If the removal was done ten years ago and there are no signs of stress to the structure then it was most probably done correctly . The only way to find out is to remove part of the ceiling and look for a RSJ. ( rolled steel joist) this support is specified by an engineer to exact specifications . A mortgage company may refuse a loan based on what you have told me , your future insurance company may refuse to insure the house if they know ! You could be stepping into big trouble on this one . Get the vendor to employ a structural engineer to pass the work or you may end up doing it again at your own cost . Be very careful about buying this house .