The figures were revealed after the deadline passed for businesses with more than 250 employees to submit data on mean and median pay gaps to the Government.
Some 78% of companies said they have a gender pay gap in favour of men, with 14% saying they have a median pay gap in favour of women and 8% having no gender pay gap.
The gender pay gap is calculated as the difference between the average salaries of men and women but it is not the same as equal pay, where firms are required to pay people doing the same job the same salary, regardless of gender.
More than 10,000 companies submitted data, with more than 15% doing so between 4pm Tuesday and the deadline at the end of Wednesday.
The Government Equalities Office, which is overseeing the process along with the Equalities and Human Rights Commission, was unable to say how many companies had been expected to file.
There were a string of amendments in the run-up to the deadline amid suggestions data had been uploaded incorrectly.
The figures suggested Millwall Holdings PLC the parent company of Millwall FC, reported a gender pay gap of 80%; GoToDoc, which runs GP practices, urgent care and after hours dental services in the North West had 77%; and women’s underwear chain Boux Avenue had 75.7%.
In its report, Boux Avenue said: “The part-time working patterns within the stores are particularly appealing to female colleagues and these roles are paid on an hourly basis, whereas the small proportion of male employees are in salaried roles.”
The list of the worst pay gaps is rounded out by recruitment firm Fusion People (73.3%), heating contractor Aaron Services (73%), Malling Health (73%), Ryanair (71.8%), Connells Survey and Valuation (71%) and East Midlands-based Fosse Healthcare (69.8%).
Fusion People said: “As we work predominantly in the construction and rail sectors, our market has been historically dominated by male workers due to the nature of the work.
“We have found that most of the jobs filled by females tend to be clerical and at a lower hourly pay rate.”
Ryanair has previously said its high pay gap is because most of its pilots are men – 546 compared with just eight women.
Of the employers with more than 20,000 workers, Lloyds Bank had the largest median pay gap at 42.7%, followed by the Royal Bank of Scotland (36.5%).
On the other hand, American Airlines had a gap in favour of women (-3.9%) as did British Telecommunications (-2.3%), while those with no pay gap included Primark, Costa and McDonald’s.
There has been some criticism of the method as a way of measuring pay disparity because it does not break down comparable roles, age, experience or time taken off work.
There have also been a number of companies which had to re-file their details due to misinterpreting the methodology for calculating the pay gap.
A spokesman for the Institute for Fiscal Studies warned that a “greater understanding of (the gender pay gap’s) determinants are needed”.
They added: “The statistics are limited and need to be interpreted with care.”
Companies who have not filed their pay gap figures will face legal action including court orders and fines, the government has said, but they are to be given a month’s grace first.