Franco's role strangely enough was in personally deciding to allow the bikini in Benidorm.
The person most responsible for the development of Benidorm from a fishing village into a large modern holiday resort with sky scrapers and masses of foreign sunbathers, including bikini-clad ones, was a man called Pedro Zaragoza Orts. He was the mayor of Benidorm in the 50s and 60s and the development of the place in that period was basically his great project.
Pedro Zaragoza Orts - Wikipedia, la enciclopedia libre
He was of course a member of Franco's strange amalgamation of a party
la FET y de las JONS. I don't think you had any chance of being mayor in those days if you were not a Franquista. But he came into conflict with the movement when he decided to let women wear bikinis. As well as the movement's opposition, he also had the opposition of the Civil Guard and of course of the Church. The Archbishop of Valencia tried to get him excommunicated.
He thought that allowing bikinis was so important to his project of attracting glam foreign tourists to Benidorm that he asked for an audience with
el caudillo himself. He set off on his Vespa from Benidorm and rode all the way to Madrid, turned right and continued on to the Pardo (Franco's lair) to the north west of the city, had his audience with the dictator and persuaded him that, for economic reasons, yes, he would allow the indecency of the bikini in Benidorm.
(When I first came across this curious little story years ago I thought there really ought to be a film made about it. I now notice in the Wikipedia article about Pedro Zaragoza Orts that a film has been made. Apparently it's called Bikini and was made in 2014.)
BTW, just on the subject of segregation in Benidorm, I believe there is a sort of informal voluntary beach apartheid there. There are two big beaches with the old town between the two. One of them, Levante, is largely British, while the other, Poniente, is largely Spanish.