It is not compulsory however we would recommend that you do as it will help you to feel included and a part of the event on the day.  Everyone wearing the blue tops is what creates the supportive atmosphere in the park and everyone has fun spotting the blue tops as they make their way around the park (particularly the children so please do make the effort if you can!).  

If it is someone's first time and they feel a bit nervous about standing out as having alopecia, then it is perfectly understandable that they may not feel entirely comfortable wearing the blue tops. But trust us when we say they might feel differently on the day which is why we recommend getting a top just in case! It helps to have any accompanying friends and family in the blue Alopecia UK tops too. Power in numbers!

You can read a bit more here under Useful Information.