There's nothing to stop you trying to do this, but there's no guarantee that that official would be still in the same role in the same office. However, the paperwork that s/he saw of yours should be listed in your old case records, and some of it will have been scanned into the system, so it should be possible to draw attention to it for a new application. It's not as good as if you had copies, and could mention, 'Originals with my case (details), London office,' but it could be better than nothing.