Pickpockets operating in the mu seum

I visited the museum today and my wallet was stolen in the restaurant at about 1315hrs  on investigation I discovered that the thief visited lager rum? And attempted to buy several drinks several times before returning to the museum at 1605hrs and tried to my CC to get back in  it was declined and I was notified  he obviously decided that it was worth returning for an hour to find another fool like me!  I believe the criminal is about 6feet tall thin with black hair and was wearing a black jacket I only saw him from behind as he sat behind me and kept pushing his chair back to mine   I had my coat hanging on the back of the chair  I registered the theft at the help desk who gave me card with number to ring on tomorrow which I will do but their apathy made me think they won't follow up to ensure you don't get the same experience  maybe they haven't on the entry kassa and could identify the s**t for the police?  Its obviously a place for rich pickings for him and his mate   I think there were 2 of them