In a 2017 interview on Australian radio station Triple J for the segment Take 5, McCartney said that the song was actually about his experience meeting Linda's father:
There’s no telling where you'll get ideas from and we happened to name this little black puppy Jet. Again I was noodling around, looking for an idea and thought that's a good word 'Jet'. So, I wrote the song about that. Not about the puppy, just using the name. And now it's transformed into a sort of girl. It was kind of – a little bit about the experiences I'd had in marrying Linda. Her dad was a little old fashioned and I thought I was a little bit intimidated, as a lot of young guys can be meeting the father figure. And if the dad's really easy-going, it makes it easy. It wasn't bad but I was a bit intimidated, probably my fault as much as his. Anyway, the song starts to be about the sergeant major and it was basically my experience, roughly translated. I never do a song with the actual words that actually happen, because then that's like a news story. Oh Linda, I was going to see your dad and he was intimidating. A bit boring. So, I mask it and mould it into a song, something you can sing reasonably
In a 2017 interview on Australian radio station Triple J for the segment Take 5, McCartney said that the song was actually about his experience meeting Linda's father: