The orange arrows point to the arris, the 90 degree angle at the front of the wooden window sill of #1 Oxford Court which was replaced and painted by Armour Hart contractors in 2011. You will note that the paintwork has failed at the arris because the angle of the arris is too sharp and creates a weak line in the skin of paint. Good practice dictates that the arris should always be rounded off with a “bull nosed ” profile.
Despite the widespread and clear evidence of bad practice in the 2011-2012 HHGE external decorations the same Armour Hart workmen who carried out the 2011-2012 Decorations were hired to make exactly the same mistakes in the 2019 -2020 HHGE decorations.
Note that the blue arrow points to the rotten wood hidden by paint at the base of the mullion (the upright support) in the wooden window. This has failed because untreated softwood was used (in 2012) to cover up existing rotten wood in the interior of the mullion. Exactly the same shoddy and unacceptable practice has been used on most of the windows repaired on the HHGE in 2019-2020. See this example at 3 Essex House which was repaired in August 2020. For another example of shoddy mullion repairs in 2012 see these examples at 8 Oxford Court where the rotten wood in the mullion has been exposed