The Second Boer War (11 October 1899 – 31 May 1902), was a conflict fought between the British Empire and the two Boer republics, (the South African Republic and the Orange Free State) over the Empire's influence in Southern Africa from 1899 to 1902. 

Starting in October 1899, the Boers placed Ladysmith, Kimberley, and Mafeking under siege, and won a string of victories at Colenso, Magersfontein and Stormberg.

It was not until the black week of Colenso that it was fully brought home to the British leaders and the nation off the war in South Africa. The news of the defeat found the passages of the War Office crowded from with those wishing to offer their services in whatsoever capacity they might be required to undertake, so great was the demand that the War Office was forced to take some action although no plans existed for the raising or equipment of volunteer forces. At this time, the greatest demand was mostly for mounted troops and a committee of Yeomanry and retired officers was formed to raise the force of Imperial Yeomanry, the royal warrant authorising the formation of this corps being signed on 24th of December 1899.

Through the Royal warrant, Imperial Yeomanry regiments were raised around the country and 3 new Yeomanry regiments were raised in London.

• 1st County of London Yeomanry (Rough Riders)

• 2nd County of London Yeomanry (Westminster Dragoons)

• 3rd County of London Yeomanry (SharpShooters)

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In the opening stages of the war, the Boers launched successful attacks against British outposts. In response to these developments, increased numbers of British Army soldiers were sent by the government to Southern Africa and under the new command of Lord Roberts and Lord Kitchener, who then relieved the three besieged cities and invaded the two Boer Republics in early 1900 at the head of a 180,000-strong expeditionary force. The Boers, aware they were unable to defeat such a large force, changed tactics and changed from fighting pitched battles to hit and run tactics, allowing the British to occupy both republics and their capitals, Pretoria, and Bloemfontein.

Though not always a success, the experiment of the I.Y. in South Africa did teach the Government and Army valuable lessons. It had showed that volunteers could serve alongside regulars with only a few problems, a lesson that proved vitally important just over a decade later when a new threat arose. In that conflict the problems that had arisen with the I.Y. were foreseen and a huge volunteer force left the UK to fight overseas.

The Regiment was raised in 1901, with the Regiment under command of Lt. Col C. R. Burn formerly of the 1st The Royal Dragoons, who was largely responsible for its formation, to meet the needs identified during the Boer War for a body of trained mounted infantry, with Colonel C. Larking as Honorary Colonel, formed as the 2nd County of London Imperial Yeomanry and enrolments started in October.

The 2nd County of London Imperial Yeomanry provided 800 to 1000 trained soldiers to the Imperial Yeomanry, it had a strong nucleus of men from 35th, 38th and 39th Battalions Imperial Yeomanry. During the period between the regiment’s founding and the end of the Boer War.

Those who were trained served across the Imperial Yeomanry Divisions and in the 28th Battalion imperial Yeomanry (2nd County of London Imperial Yeomanry, in 127th, 128th, 129th and 130th company). 

Many of those who served in South Africa rejoined the reformed 2nd County of London Imperial Yeomanry on their return. So, although they never served as a Regiment in South Africa, many of its earliest members had done so.

Having been recruited and trained as 2nd County of London Imperial Yeomanry. For this reason, they carry on their Guidon the battle Honor 'South Africa 1900-1902'.