Group 1 - rear facing car seat - Recommendations please

How heavy is your 15 month old? You need to have a look at the growth charts in their red book and see roughly what age they are going to be when they hit 18kgs.

The reason for this is that you need your child to be at least 4 years old before you consider moving them to a forward facing high backed booster, and preferably closer to 5.

99% of ISOFIX seats have an 18kgs weight limit, so if your child is above the 70th centile line for weight you'd need to be looking at a seatbelt-fitted seat with a 25kgs limit (you can't count all the Joie seatbelt-fitted options in that because they are the exception and can only be used rear facing to 18kgs) in order to keep them rear facing and in a 5-point harness until they are at least 4.

So have a look at your child's predicted weight age 4 and go from there.

I have a Britax Multi Tech II seatbelt-fitted seat for my daughter who will be 5 next week. She is very happy in it, and I love it because the sides are quite flat so it's much easier to get her into than a more 'bucket' shaped seat. She is very small for her age (not yet 15kgs, she's below the 9th centile for height and weight) so we also have a Joie Stages that we can still use rear facing for her. That's a great seat too.