Little Queenie, would you describe the riding-up skirt as a type of Tattersall check? My mum had a hairdresser c. 1964/65 (who I fancied like mad but she was a few years older than me!) and she wore such skirts. She was a mod.
Twiggy was wearing Fair Isle in that style in the mid sixties. I recall men wearing a similar style at that time.
I note too the style of hair the girls are displaying is typical of the earlier 60s. I would think 64 is about right for that pic.