They might fly a fair few more than 24; 24 IPS means you need to put more in.
As far as basing goes, I don't fancy flying Tucanos at Valley without an immersion suit, and it's not cleared for them (or at least wasn't when I last flew one). Cranwell, sure; but with the messes traditionally full, accommodation across Lincolnshire full (Waddington appears to be overflowing everywhere) and no new facilities to base a squadron of Tucanos from, where would you put them?
And, thinking like an Air Officer, would sorting those problems be cheaper than just running Linton for a few more years until it's your successor's problem...?