A Chinese national who acted as a property agent for criminal gangs in Britain, renting hundreds of houses to be used as brothels and cannabis farms, was jailed on Friday for seven years and four months by a court in Birmingham, the UK’s second-largest city.

Feng Xu amassed around 5,500 forged documents – including driving licences, bank statements, wage slips, utility bills and dozens of fake or fraudulent Chinese and Portuguese passports – to secure tenancy agreements on at least 446 properties, according to British police.

The 43-year-old’s crimes were on a “colossal scale”, said Judge Francis Laird, who noted that Xu had acted as an ersatz “estate agent” for criminal gangs, keeping meticulous records of all the properties he managed on a spreadsheet found on his computer.

The case at the city’s Crown Court cast a rare spotlight on the vast network of Chinese criminals operating in the UK and the sophisticated methods they use to avoid detection.

Some of the properties that were used as brothels were staffed by Chinese women who had been trafficked and forced into prostitution, the court heard.

Xu personally made an estimated £1.1 million (US$1.4 million) from his criminal enterprise over the course of three-and-half years by charging £2,500 per property arranged, prosecution barrister Bill Baker told the court, with police finding £94,200 in cash when they raided his home and a rented storage unit.

Examples of the properties Xu arranged, for which £4.2 million in rent was paid, included a one-bedroom cottage in the wealthy spa town of Cheltenham that was used as a high-class brothel staffed by two Asian women, and an elegant town house in the southern seaside town of Worthing, with a view of the pier.

Originally from the sprawling southern Chinese metropolis of Guangzhou, Xu moved to the UK to study almost 23 years ago with dreams of becoming a businessman, but after his leave to remain expired in 2000 he was forced to undertake menial jobs and incurred heavy debts when an online business he set up selling karaoke equipment failed, his barrister Gurdeep Garcha said in mitigation.

It took more than 30 police forces up and down the country to finally catch Xu following a series of brothel raids triggered by adverts on Chinese websites and complaints from neighbours.

By swapping notes, officers noticed Xu’s picture – or that of someone who looked a lot like him – on many of the tenancy agreements, alongside a long list of fictional Chinese names.

They were eventually able to track him down to a flat in Birmingham by tracing an electronic rent payment he made for a property used as a cannabis farm back to his IP address.

Although the vast majority of properties Xu secured were used for prostitution, he also organised safe house for illegal migrants and acted as a property agent for cannabis growers, finding larger secluded premises in the countryside.

Garcha, his barrister, said Xu was relieved to have been caught “as he had been living a life in the shadows for a number of years” and was “ultimately a facilitator” for people “higher up the chain” who used the properties for crime.

The National Crime Agency – Britain’s national law enforcement agency – shared the view that the case “goes way beyond one man”, but noted in a statement that “in taking Xu out we will have caused significant disruption to a number of different organised crime groups involved in prostitution, people smuggling and drug production.”

“While he wasn’t necessarily involved in those types of offences himself, he was an important enabler for those who were.”

Xu pleaded guilty last October to 22 different offences, including possession of documents used in fraud and money laundering. He will face deportation after serving his sentence, which was cut by one-third for his early guilty plea.