Watch: What is the Queen's Truncheon and the Gurkhas' Kassam Khane parade?

Every year, a new set of Gurkha recruits pass out and join their assigned regiments.

One special ceremony they take part in as part of the process is the Kassam Khane parade.

After taking their place on the parade square the trainee soldiers pledge their allegiance to their regiment, as well as the Queen.

In groups of three, the troops pledge their allegiance by touching the Queen's Truncheon – a ceremonial staff carried as the equivalent of a colour.

Watch: Becoming a Gurkha – the last test.

Treated with great reverence, the Truncheon was originally presented to the Sirmoor Rifle Regiment by Queen Victoria in 1863.

The Gurkhas must also take an oath in which they swear to "be loyal and uphold tradition of the Queen's Own Gurkha Logistic Regiment".

Troops cannot serve until they have taken the oath, and then must then take a secondary oath – known as the Kassam Khane parade.

Dating back to the 18th century, the format of each Kassam Khane changes depending on which regiment the personnel are joining and usually takes place shortly after the troops join.

The first Kassam Khane was held in Kluang, Malaysia, in 1962.