Do the names Vera, Chuck, and Dave - the future grandchildren in the Beatles' hit "When I'm Sixty Four" - represent real people in the life of the Fab Four?

I have a book called "A Hard Day's Write" which gives detailed stories behind all the Beatles songs, and if there are any references to real people in the songs they are discussed in there too. There is no mention of Vera, Chuck and Dave being real people or being significant in any way, so I would assume that they are simply made up 'old fashioned' sounding names which go with the tone of the song.