Thanks for your response, Saffi. As it happens he is also in the 99th percetile for height, but that is not really my concern. Kids in Scandinavia remain rearward-facing until the age of four. They just fold their legs and deal with it! My concern is, instead, that if I leave him rearward facing when the seat specifies a 12kg limit that I will be compromising his safety in another way - perhaps they have not been designed to support additional weight in that position etc. So if I cannot locate a seat with a higher weight-limit then I will have to start calling the companies and asking those kinds of questions. Hopefully someone here will have encountered a similar issue and can advise me instead