Thunderbirds Are Go! If your boys are into Thunderbirds, then they will love this Alan Tracy costume from Pretend to Bee. They are a family run business and have been retailing their range of dressing up costumes since 2005! Looking through their website, I found they have a great range of exciting children’s dress up clothing! From History costumes to Nativity costumes, Halloween to Christmas and from Dinosaur to Princess.