Complex sentence: The main typeface used on the plaque appears to be Gill's contemporaneously-designed "Perpetua"-designed in 1925, but not released until 1929-while the lower-case typeface used for the Latin quote below is not presently recognised.
Split into simpler sentences: The main typeface used on the plaque seems to be Gill's Perpetua, which he designed in 1925 but did not release until 1929. The lower-case typeface used for the Latin quote below is not presently recognised.