'These Look Fit Enough!'

Women's football was hugely popular in Britain in the first part of the twentieth century. It had had a shaky start: while an England-Scotland international in 1881 went smoothly, a second game a few days later in Glasgow ended in a pitch invasion. The spectators (over 5,000 and mostly male) objected to the quality of play and of umpiring, and turned violent; the players fled in their omnibus, with stakes thrown at the vehicle as it sped away. Newspapers announced the death of the women's game, but they were over-hasty.
In 1894, the British Ladies' Football Club was founded by Nettie Honeyball, whose motives were avowedly feminist: "proving to the world that women are not the 'ornamental and useless' creatures men have pictured. ... I look forward to the time when ladies may sit in Parliament and have a voice in the direction of affairs, especially those which concern them most." They played their first match the following year, in Crouch End, London. It attracted a crowd of 10,000 who were more tolerant than their Scottish counterparts of the standard of play (although the women had practised throughout the winter, they were hampered by nerves and very bulky outfits).
The women's game continued uncertainly on until a boost was given by the First World War, when teams of munition workers played in major venues. Many continued playing after the War, often for charity. In 1920, 53,000 spectators watched a boxing day match between Dick, Kerr Ladies (a Preston team) and St Helen's Ladies; the biggest crowd for a men's match that year was just 37,545. Such success, though, was perhaps the cause of what happened next.
The following year, the Football Association decided that the game should be male-only. They banned women from Football League grounds with the argument that "football is quite unsuitable for females and ought not to be encouraged." This (lighthearted, not to say patronising) 'topical budget' newsreel was made in response:

Sadly, the FA remained convinced by its own argument; the ban went ahead and was only lifted in 1971. Although the women's game continued - the Dick, Kerr Ladies' team was only disbanded in 1965 - it was badly damaged by the ban. Since it was lifted, football has grown hugely in popularity for women and girls but still struggles to attract anything like the attention given to the men's game.
Further reading: Patrick Brennan has brought together a great deal of information, with primary materials including photographs and newspaper reports, at this website.