Can anyone advise what size to buy for a 4.5yo school jumper? The uniform supplier sells them in 24, 26, 28 inches which means absolutely nothing to me. My child’s chest measures 23 inches, the H&M age 5 sweatshirt he’s currently wearing measures 28 inches across. But it’s a sweatshirt and is supposed to be a loose fit, I don’t know about knitted school jumpers?