Siobhan - Marie O'Connor could only muster third place in tonight 's nationals finals .
Siobhan - Marie O'Connor was the top British swimmer at last year 's Commonwealth Games in the 100 fly with a silver medal performance .
Siobhan - Marie O'Connor , who was the top British swimmer at last year 's Commonwealth Games in the 100 fly with a silver medal performance , could only muster third place in tonight 's nationals finals .