The photo above shows the current condition as at 2 December 2020 of windows at Oxford Court previously repaired in a two year program in 2010-2011 by the same team of Armour Hart tradesmen who are carrying out the 2019-2020 repairs. In 2020 these workman are using the same techniques and the same untreated softwood to repair the rotten mullions (uprights) in the wooden frames as they used in 2011, – 10 years previously. If the correct wood was used in the correct manner a window repair should last for c. 30 years.
See here for a mullion repair carried out at 3 Essex House in August 2020 (10 years later) using the same untreated softwood used to cover over rotten wood. Essex House: Rotten wood covered over with sub-standard materials 6 August 2020