The historical archives of the Grenadier Guards are held by the National Archives and the National Army Museum.
The National Archives
https://www.nationalarchives.gov.uk/
Attestations (1795-1838), enlistments and discharges ledgers, casualty books, posting books, NCOs succession books, nominal rolls, statement of services of officers (1801-1918), regimental numbers, marriages and baptisms books (1804-1908).
Please note that the records of service of individual soldiers are held by the Ministry of Defence – see Find a Grenadier Ancestor.
List of ledgers and books: Gren Gds archives at TNA
Marriages and Baptisms: Marriage and baptism books of the Grenadier Guards
The National Army Museum
https://www.nam.ac.uk/
The Grenadier Guards collection at the National Army Museum consists of ledgers, correspondence and letter books, order books, memoirs, diaries, medal rolls, courts martial (1747-1948), and photographs.
Catalogue of documents: NAM archive catalogue
Catalogue of photographs: NAM photos catalogue
The archive catalogue can be viewed on https://collection.nam.ac.uk/inventory/objects/. Enter Grenadier Guards under ‘Regiment’ and select archives only [you can deselect the other categories by simply clicking on their headings].
Brigade and Regimental Orders
Click here for a searchable index: Gren Gds Index to Regimental Orders