Good question Richard. The following is from BTO Birdfacts;
Pied Fly, average date of first arrival 19/4, first clutch laid unknown, incubation 13-15 days, fledging 16-17 days.
Redstart, 5/4, first clutch 13/5 (2/5-7/6), 13-14d, 16-17d
Redstart is more likely to have a second brood but both...