Looks like the diagnosis for my foot and knee troubles is getting clearer. Time for treatment, therapy and custom mould insteps to correct.
https://www.wsh.nhs.uk/CMS-Documents/Patient-leaflets/TraumaandOrthopaedics/6112-1-Tibialis-Posterior-Tendon-Dysfunction-or-Insufficieny-or-Adult-Aquired-Flatfoot-Deformity.pdf