The 17-year-old Barracudas backstroke ace, who holds multiple Guernsey records despite her youth, features among 71 youngsters selected for the development drive aimed at nurturing international-class talent.
Tostevin would ordinarily be based at Millfield School but is currently learning and training from home due to Covid.
As that same Covid pandemic leaves her UK counterparts high and dry without pool access, Barracudas head coach Sara Parfit gave a ringing endorsement of the hard-working youngster.
‘Tatiana has come up the whole way from the swim school, all the way through the Barracudas, before going to Millfield, so we are delighted at the success she has been getting while at Millfield,’ Parfit said.
‘We do not get that many swimmers or athletes in the island getting to that sort of level, but when you consider the size of the island, we are punching above our weight.
‘Despite Covid, I hope that she can continue her success and continue to train and improve.’
Special training camps, albeit currently online ones, are on the agenda for a youngster who recently scooped up the Lambourne Shield at Guernsey Sports Commission’s annual awards night.
Having debuted at the Commonwealth Games before her 15th birthday, Tostevin marked a return to that stage in 2022 as a key focus.
Millfield coach Euan Dale added: ‘Being great friends with Ian Powell, I know first-hand how passionate Guernsey is about its swimming and sport in general.
‘Tatiana is one of a kind. Her commitment to the sport of swimming and her passion for racing is really what separates her from the rest.’ Interview to follow