Landlord gave some homeless guy a key to my flat while i was still living there!!!!

I have been in rented accommodation in gateshead for just over two years and I am due to move out on the 1st of February 2007, I informed my landlord with two months notice that I was moving out between the middle and the end of January. On Saturday the 27th of January the prospective tenant called to my door at 8pm, he is a homeless Romanian busker and he said that he had registered this address at the local job centre, he advised me that some mail would be coming and I said that I would leave it here for him and at that point he said he would collect it on Monday. It turns out that he has a key for our flat for the last week; he viewed the flat on his own without my knowledge. My landlord had told me that he was showing the flat to someone and I had a greed assuming that he would be there with the new tenant. I called my landlord and asked him to take back the key to which he refused. I called the police fearing for my safety and was told to contact the landlord again, when I called him and told him that I had been on to the police, he hung up on me. Fortunately the busker had come back and wanted to put his bike in the cupboard, I demanded the key from him and he called our landlord and the landlord told him to give it to me so I now have all keys that I am aware of in my property.

I live with my sister and frankly I am appalled that my landlord would give a key to a total homeless stranger living in a tent, obviously because it was our home we had money, ankh cards, statements and valuables everywhere. I have been on to the landlord association, gateshead council and the police and unfortunately they cannot do anything against him. I am furious that he could put our lives in danger like that and allow a perfect stranger into our flat without us knowing, he advised the new tenant that he could come and go as he pleases. Is there anything that I can do, not only have I not slept since Saturday, I am worried about going to work and coming back to find all my belongings gone and no signs of forced entry. It disturbed me that the busker had said “the only reason I knocked was because I saw the light on otherwise I would have just used my key”. I have no idea if a copy of the key has been made and thankfully I am moving out on Thursday but I just want to know if I can stop this landlord from doing the same thing. He is a shocking landlord, the roof in my kitchen has been leaking for over five months, the gas boiler has been leaking for four and all the while he has been aware of this. I am a very patient an easy going person but the key incident was the last straw!
Any advice or help on this matter would be greatly appreciated.