From 1747 the 9th carried two Colours, the First, or King’s Colour, and the Second, or Regimental Colour. This photo shows the central device of the King’s Colour. The whole flag was the Union flag which combined the red cross of St George with the white on blue saltire of St Andrew. However, there is no sign of the saltire in this detail. The Union wreath of roses and thistles on the red cross surrounds a floreated shape that contains REGT. over IX.
This image is borrowed from ‘British Infantry Colours 1747-1800’ at https://www.62ndregiment.org/colours.htm
An inspection return of 15 July 1772 mentions Colours but they are not mentioned in the return of June 1771 so the 9th probably received the Colours in 1772. The 9th fought in North America soon after that and were forced to surrender at Saratoga in 1777. The CO of the regiment, Lieutenant-Colonel Hill, saved the Colours from being captured by the Americans. He removed them from their poles and concealed them in his personal baggage. On his return to England in 1781 he presented them to the King and was rewarded with promotion to colonel. The Americans were not happy and claimed that this was a breach of the Convention, and as a result was partially the reason that the Convention was not ratified.