£30 in Asda, still £65 in Argos and mothercare!
Decent brand, Britax are well known for exceeding the very basic safety regulations on car seats.
Height adjustable backrest, narrow but tall seat. Deep padded wings on the headrest provide good support for a snooze and head protection.
It has side impact protection too.
Good fit in a lot of cars, no arm rests so it fits better between other seats and it tapers towards the back so you can see the buckle when you need to clip the safety belt shut.
Reviews are good on amazon https://www.amazon.co.uk/Britax-Romer-Adventure-Highback-Booster/product-reviews/B00AE2OAN2
Car compatibility checker / Britax fit finder http://www.britax.co.uk/car-seats/fit-finder