I saw someone that I'm sure I've never met before into my flat

On Friday I got a let's not meet and I'm extremely confused, and would love someone to tell me if they've ever heard of this happening.<br><br>I live in a flat, one of many in a block in London. My boyfriend and I are moving out in a few months to go to the countryside. As a result, I have been selling furniture and stuff online, and I am due to move out for 3 months to stay with family on the other side of the country until we move in August.<br><br>So, I have people coming to look at the place I will be moving out of on Friday to see the place and if they might be interested when I move in July to move in. I have already spoken to one girl who has seen the flat and she is extremely keen, and I am pretty sure she'll take it.<br><br>Anyway, I had an email from another girl who wanted to come over on Friday to see the place. I was at work, so was my boyfriend, we were going to a friends birthday dinner in the evening so could only accommodate a visit in the evening. She said that was fine, and she would come at 7pm. We said that we would be there too, and it was to be quick as we were going out so wouldn't have much time. She said that was fine too.<br><br>My boyfriend left work at 5pm to meet me at 5.30pm at our flat. I got off at 6pm and got home at 6.15pm and my boyfriend was already there. We went to put some cream on a sofa and chair so we went into the bedroom where they were and closed the door. There are floor to ceiling windows in the living room, so you can see pretty clearly into the living room from the corridor. We were in the bedroom for 10 minutes.<br><br>When we left at 6.25pm to go to the birthday dinner, we greeted the birthday boy and girl and they immediately said that they thought we were already there as they had seen the flat door open and us letting someone in off the corridor, we said no, that we weren't there, and they insisted again saying that there was someone in our flat, and that whoever it was was in the middle of moving out as they saw stuff being moved around and the place being tidied, and that they thought it was us. We went down to the flat and checked, the girl hadn't turned up. But everything was tidy, nothing had been stolen, and there was no one there. It was exactly as we had left it, with the exception of some cream we had left that was slightly mud-like having been opened. It was as though whoever it was had been sitting in the place and using something from our flat. Like they had used the place to hang out for a while. <br><br>I emailed the girl who was supposed to come over asking where she was and she said that she wasn't in London and would be in touch to reschedule.<br><br>The most confusing thing about all of this is that we are 6 floors up, and our flat door isn't a push door, it's a pull door, which can only be opened by a key or the key card. Which not even the refuse guys have - we have to leave them on the doormat.<br><br>The only explanation I can think of is that someone in the block saw us going into the flat and into the bedroom and assumed that we weren't there and used the key card to get in. But if they were trying to steal stuff, and had the key card, surely they would have already struck by now? And what's with the cleaning? And when we move out, surely they couldn't do this for much longer as the new people moving in will know what they're doing and there will be no reason to be in the flat meeting people.<br><br>I have contacted security for the flats and they said that if we want to get to the bottom of it we need to make a police report, but it's a lot to think that someone is just coming and going into my flat. And there's no proof to suggest that it is anyone in the building. <br><br>Is there anyone on here who has ever come across anything similar, and if so, how did you handle it? And did anything happen as a result?<br><br>&#x200B;<br><br>EDIT: If you're going to comment and tell me that this didn't happen and that I'm lying, please just fuck off and go comment on another post. There's no point in me posting it here at all if no one is going to have anything useful to say.<br><br>&#x200B;<br><br>TL;DR: Someone came into my flat after I had left and tidied up and left again. We have no idea who this is and is getting creepy to the point where we don't want to move out now.