The Grey Partridges were all juveniles in full moult, (all had a primary moult score of 28). Juveniles undergo a complete post juvenile moult except for the outermost 2 primary feathers (Ginn & Melville: Moult in Birds). They also have dark bills and the red on the head was just starting to appear.
The other birds, caught in the roost, were Pied Wagtail and Reed bunting. The photo of a juvenile Pied Wagtail below shows it is still retaining some of the yellowish feathers on the head and 6 juvenile greater coverts.