The co-founder of a children's soft play company spied on dozens of women after "stalking" schoolgirls from a swimming lesson, a court has heard.
Former Eddie Catz director Darren Johnson, 51, used "peepholes" to film women in toilets and changing rooms at a centre where parents take their young children to have fun.
The married father-of-two also followed youngsters when they attended a leisure centre for swimming lessons before using a mobile phone to look under their cubicles as they changed, Kingston Crown Court heard.
Johnson, from Putney, was finally caught when two 14-year-old girls spotted his iPhone 6 from under the adjacent cubicle and alerted staff.
He was identified from CCTV footage and police seized two computers containing hundreds of images of women in various states of undress.
Johnson admitted five counts of voyeurism over a period of 12 years, between January 1, 2005 and June 5, 2017, although his barrister Tom Williams said his offending occurred over "a few months" in 2007 and a second period in 2016 and 2017.
But he backed down on claims Johnson had not meant to film teenagers after prosecutors refused to agree.
Prosecutor Lauren Sales said: "There is CCTV which shows the defendant stalking children around the leisure centre. He attended the leisure centre at times when schools have swim classes.
"He goes up to the swimming pool, sees the kids, sees them using the facilities, stalks them to the shower area and stalks them to the cubicle area and uses the cubicle next to them.
"There was a 12-year-old he was following as well. It is all shown very clearly on the CCTV."
The court heard no charges were brought in relation to the 12-year-old.
Ms Sales said: "At the time of the offences, he was the director of Eddie Catz, which are soft play centres for young children."
The number of victims is not known, although a police officer involved in the case estimated it could be around 40.
Judge Andrew Campbell said: "We are certainly running into the tens, twenties and possibly very many more."
Johnson, who founded the firm with his wife Maria, resigned from the business as soon as the allegations came to light and he has not been listed as a director since September last year.
The company has centres in Earlsfield, Putney, Wimbledon and Newbury, as well as a presence in branches of Mothercare in Leeds, Gateshead, Manchester, Solihull and Cribbs Causeway, near Bristol.
Johnson's lawyer said his client had enjoyed a successful sporting career, which took him to Italy, but was plagued by alcohol problems and marriage troubles after he was injured.
He said: "He accepts what he did was completely wrong and, now he is able to think through it in a way that makes a bit more sense, he is truly sorry for what he has done and has done everything he can to address those things in his life which pushed him into an extremely dark place in that period."
Mr Williams said Johnson had attended Alcoholics Anonymous meetings and classes for sex addicts since his arrest.
The judge said he would sentence Johnson on Wednesday.
Two of the voyeurism charges relate to the filming of the 14-year-old girls, while a third relates to images of women taken under cubicles at the leisure centre.
Two further charges relate to images of women taken through "peepholes" and under cubicles in toilets and changing rooms at a soft play centre.