I have the same age gap Miss E, and I've never had nor needed a double pram. I didn't like the look of the skateboards so I went without. I'm a baby wearer though. I still put one of my kids in a carrier if needed (Ayers Rock is a good example).
I used to sling DS and DD would hop in the pram. That was because she was a bolter. But she wanted to less and less so for a while I got away without having to lug one at all. I live in the country though. She was also became very good at holding onto the safety strap of the pram without running away when DS needed to go in the pram.
I'm not getting a double this time either and my age gap will be the same again.