A man barricaded himself into a cannabis factory in Harrow after police attempted to raid it.
Cops swooped on the detached five-bedroom house in Kenton Avenue today (Wednesday) but the suspect, who initially locked himself in the house, managed to escape.
It is believed the house had been owned by three ladies for more than 80 years but was sold last month following their deaths.
David Harris had been visiting his mother, who lives next door, when the raid happened.
He said: "I didn't think anyone was living there.
"They all came in and painted it a few weeks ago and I haven't seen anyone since."