Byron House children should come to school wearing PE or sports kit on days that they have these activities. On swimming days, they should come to school wearing normal uniform and bring swimming kit. In practice, this means that some children will spend more time in their tracksuits than in their full school uniform, which you may like to consider when deciding on the amount of uniform to purchase.
Senior House children should come to school wearing sports kit when they have Games on a particular day. If they have PE (unless they have Games as well), they should come in wearing normal uniform and bring PE kit with them.