This happened to a close friend of mine about a few months ago. She told me a very similar story and I wonder if it's the same guys. There were three men. One came in first on a booking, probably to reccy the flat before making an excuse to leave. He let in the other two, then the three of them made threats, struck one of her friends when she refused to cooperate and made away with cash, laptops and mobiles. The same three guys returned two weeks later and did the same thing again.
She said she reported it to the police on both occasions.
Another friend of mine had an attempt made a few weeks later. She is also located in the Baker Street area. She screamed and let off a loud panic alarm. They ran away.