They are 11-year old Adam John and his 8-year old sister Amy. To the best of my knowledge, this is the first time that a brother and sister from Suffolk have both been selected to play for their country.
Adam, currently graded 131, is having a good season in the leagues and may hit 150 in the next grading list to be published in July. Meanwhile, sister Amy (ECF 74) has started playing regular league chess. She is showing tremendous concentration and most of her games are lasting over two hours.
Congratulations to both on being selected! The website for the Championships can be seen here.