4 Trooping the Colour - Escort to the Colour 

Part 4 - Escort to the Queen's Colour of the Scots Guards
360 years of Trooping the Colour - Queen Elizabeth II's Birthday Parade 2011
BBC
The music is provided by the Massed Bands of the Foot Guards and the Mounted Bands of the Household Cavalry, together with a Corps of Drums and occasionally pipers, totaling approximately 400 musicians.
To the strains of "The Grenadiers' Slow March", the Escort To the Colour then troops the colour down the long line of Nos 6-2 Guards. The colour itself is borne by the Ensign in front of the line of Guards, but the ranks of the Escort interweave with their ranks. For Nos 6-2 Guards, who maintain the 'present arms' position, the long trooping, especially on a hot day, requires stamina.
Eventually the Escort arrives back at its original position as no. 1 Guard - from where it first marched off in quick time. Their Captain, who had temporarily ceded his command to the Subaltern, resumes his command over No. 1 Guard by ordering them to present arms, thus bringing the Escort back in line with Nos 2-6 Guards. The entire parade is now ordered by the Field Officer to slope arms, thus concluding the Trooping phase.
The Trooping phase is followed by the March Past in Slow and Quick Time of the Foot Guards and then the Household Cavalry with King's Troop, also in slow and quick time.