Yes, the Foot Guards had the Union Flag (which were company or 'captain's' colours in the Guards) on the left and the crimson colour (known as the colonel's, lieutenant-colonel's or major's colour) on the right.
The 1st Foot Guards could also carry a third colour, known as the Royal Standard if the King was present (which was another fairly plain crimson flag - not the quartered Royal Standard flown from palaces), though that wasn't carried in the field after the War of Austrian Succession. Some Militia regiments also had a third colour where the county had more than one Lord Lieutenant.