Jonathan wrote:
Is there anything I can do about it now, or is it too late?
(they are against a south facing wall)

My experience of brown turkey figs is that these are fruit that will
ripen next year. This was on a south-facing wall in a very exposed
spot in the Cotswolds.

Oh right, so the unripe fruits will sit there over winter and then grow on
/next/ year? I would have expected them to drop off when it frosts!