81st Regiment of Foot

Chronology

1793 raised as the 81st Regiment of Foot
1802 absorbed the Loyal Lincoln Volunteers (Villagers)
1832 became the 81st Regiment of Foot (Loyal Lincoln Volunteers)
1881 amalgamated with 47th (Lancashire) Regiment of Foot to form The Loyal North Lancashire Regiment
1970 amalgamated with The Lancashire Regiment to form The Queen's Lancashire Regiment
2006 amalgamated with the King’s Own Royal Border Regiment and the King’s Regiment to become the Duke of Lancaster's Regiment (King's Lancashire and Border)

The British Library has the books

The Loyal North Lancashire Regiment, in 2 Volumes, by Colonel H. C. Wylly 1933
A short history of the Loyal Regiment 1965

81st Foot Wikipedia
Loyal North Lancashire Regiment Wikipedia
81st (Loyal Lincoln Volunteers) Regiment of Foot including
- deployments Regiments.org, an archived site.
The Loyal Regiment(North Lancashire) including deployments:
- 1st Battalion and 2nd Battalion Regiments.org (archived site)
The Loyal North Lancashire Regiment from the Long, Long Trail: the British Army in the Great War of 1914-1918. The 2nd Battalion were in Bangalore in August 1914 and landed at Tanga, German East Africa, with the 27th Indian Brigade 3 November 1914
Queen's Lancashire Regiment Wikipedia
Lancashire Infantry Museum, includes the East Lancashire Regiment (30th and 59th of Foot), the South Lancashire Regiment (40th and 82nd of Foot), the Loyal North Lancashire Regiment (47th and 81st of Foot)
“The Regimental History of the Duke of Lancaster’s Regiment” army.mod.uk

The constituent regiments are the 4th, 8th, 30th, 34th, 40th, 47th, 55th, 59th, 63rd, 81st, 82nd and 96th Regiments of Foot.