Over the past six months police have busted 72 cannabis factories across Barking and Dagenham, Redbridge and Havering and officers are asking "would you know if there was one next door?".

Police have issued a guide for a number of signs to look for:

Bright light – The cultivation of cannabis plants requires a lot of light running at around 12 hours per day. The lights are incredibly bright so a tell-tale sign is any property where windows are constantly blacked out or curtains that are never opened.

Fans/Ventilation – The farmers need to ventilate the plants they are cultivating and they do this using large extractor fans which make a low humming sound. Routine use of a fan such as this, particularly in autumn or winter, would be an indicator that a cannabis grower may be operating at the property.

Smell – While it takes three months to grow a crop of cannabis, it is during the final month that the smell becomes overpowering – it is pungent and quite literally stinks.

Comings and goings – Many cannabis farms don’t have anyone living at the address; be aware of people coming and going at strange times and not staying for long.

Detective Sergeant Owen Morgan, of the East Area Command Drugs Focus Desk, said: “We have seen an increase in the number of cannabis factories throughout the pandemic and are working hard to identify and dismantle them.

“We have significant concerns that growers tamper with the electrical supply at the venue and this, combined with the chemicals used in growing the plants, can be a significant danger to neighbouring properties.

“Cannabis growers are in constant fear of being robbed by other criminals who want to steal their crop. For this reason they often increase security on the address which may include additional locks, grilles and even CCTV cameras.

“In addition to all of the above, the cultivation of cannabis fuels organised drug-related crime and drug use – both of which can seriously reduce the quality of life for local people.

“It is clear that a cannabis factory is not something that you want in your street where you may be living, working or raising a family."

If you believe there may be a cannabis factory operating close to your home, you should call 101 or speak to the Neighbourhoods Police Team.

You can also report it anonymously via Crimestoppers on 0800 555 111.