A cannabis factory set up in a Greenford car park was busted after a park guard alerted police to a "constant smell" coming from the area.
The converted garage in Greenford Road was discovered by Ealing Metropolitan Police on September 9 following a tip off from a patrolling park guards officer about the distinctive smell.
Officers headed down to the car park after getting the call at 12.28am and were pointed in the direction of a burning light through a window.
After entering the garage, a man and woman were found inside the factory, along with eight cannabis plants grown in the tent.
A spokesperson for the Met told getwestlondon: "The male and female were arrested and later received a police caution for the production of cannabis."
The plants were seized to be destroyed.
Greenford police officers praised the patrolling guard in assisting them with the arrest.
On the same day, officers were at Ravenor Park in Greenford where they stopped two males, one of who "quickly tried to dispose of three bags of herbal cannabis".
However, they handed over "a further two bags and a half smoked joint", according to the Met.