[3] At the same time, Lawrence also ordered irregular force of mixed cavalry and infantry: the Corps of Guides to be raised at Mardan by Lieutenant Harry D.

In 1903, the reorganisation of the British Indian Army caused the four Sikh regiments to be re-designated as follows: 51st, 52nd, 53rd and 54th Sikhs (Frontier Force) while the Corps of Guides infantry became Queen Victoria's Own Corps of Guides (Frontier Force) Infantry, and was renamed again in 1911 as Queen Victoria's Own Corps of Guides (Frontier Force) Lumsden's Infantry.

The location of the training battalion, later to grow into the Regimental Centre, was first at Mardan but moved to Sialkot in 1929.

[5] The new structure of the regiment by 1939 was therefore as follows:[6] During the Second World War the regiment's battalions (expanded in number by seven war-formed units) saw service in East Africa, North Africa and the Middle East, Italy, India, Malaya and Burma.

[8] In the autumn of 1940 the battalion transferred to the Delhi Cantonment[8] and on 15 May 1941, the battalion was transferred to the 17th Indian Infantry Brigade, part of the 8th Indian Infantry Division which was being raised in Bombay, and with which it remained for the rest of the war.

The commanding officer of the 2/12th FFR, Lt.Col.Arthur Edward Cumming, received the Victoria Cross during this campaign.

[9] The 3/12th FFR was part of the 5th Indian Infantry Division during the East African and Western Desert Campaigns.

[9] The 5/12th FFR served throughout the Second World War as part of the 6th Indian Infantry Division on garrison duties in Iraq.