Morris Men?

This is a picture of a group of men lined up on a lawn, all dressed in similar clothing and, to my mind, obviously waiting to perform in some way. I've called the picture Morris Men because I wonder it that is what they are, but I'm not sure that is the case. Another interesting clue in the picture is that they all have writing on their trousers and the writing seems to be possibly Manx?

The date on the slide mount is Jan 1964, but the picture doesn't look like winter so I think this was probably taken in the summer of 1963 and processed at the end of the year. Anyone who has some proper information about what is going on here please let me know with a comment below.