Once listed for preservation, it was decided that another 'Arthur' might be a better proposition. 'King Arthur' was considered to be in need of much too much work to be a viable candidate*, although much soul searching went on at the time. 30770 'Sir Prianius' and 30777 'Sir Lamiel' were said to be in much better condition. When 'Sir Lamiel' was withdrawn, it was found that he carried a boiler in very good condition, a major consideration, which had last been carried by 30454 'Queen Guinevere,' and had been extensively overhauled to keep as a spare. Therefore 'Sir Lamiel' was put aside for preservation instead of 'King Arthur,' and 'Sir Prianius' was left to soldier on, as the last working survivor through 1962.
*(This was the official version, but I suspect that a 'Scotchmen' Arthur with the later Maunsell cab, was considered to have a much better route availability, being lower and more in gauge than the Urie pattern "Cathedral" type cab.)