redmark
Squire
Not sure the base chance is zero - I'm sure I've recruited t5 prisoners in the past and I think a few t6 too (Fian Champions), but rarely. Without looking at the code, it's always felt as though a) the longer you have a prisoner, they less likely they are to recruit and b) you're more likely to recruit a t4+ prisoner if you only have t4+ prisoners; the lower the tier, the higher chance to come up for recruitment, total number recruited per day is capped (2 or 3?), so having a range of prisoners from different tiers is 'blocking' (significantly reducing odds) the higher tiers from recruiting. But again - not looked at the code.Is that a bug or hasn't been implemented though?
The way to test would be to capture some new prisoners, and *only* hold onto t5/t6 ones for an ingame week or two.