Military and Medical Links
Army Medical Services and the Malta Garrison - an excellent set of articles.
Historical Record of the Fifth Regiment of Foot, or Northumberland Fusiliers - An accounting of the postings and campaigns of the various battalions of the regiment from 1674 till 1837
The 66th Berkshire Regiment - An accounting of the postings and campaigns of the various battalions of the 66th regiment from 1758 till 1881
Roll of Commissioned officers in the Medical Service of the British Army- a listing of all the medical personnel who were commissioned from 1727 to 1898. The listing shows the first year that a medical officer was commissioned (usually as Assistant Surgeon) and their duty post (regiment, in most cases), and then their subsequent postings until death or retirement. There are also notifications for Peninsular service and half-pay/full-pay status. Once you get the trick of the short-hand, it is easy to find out who was in each regiment. The only confusion is that there are no records of battalion, and as there could be up to three medical officers (one surgeon and two assistants) per battalion at any time, figuring out who was where and when can be tricky. I have made a chart for the 5th and 66th.
British Regiments and the Men Who Led Them: 5th Regiment of Foot - The Napoleon Series in general is excellent for information on the various aspects of the wars, no matter which side you are interested in. This page in particular lists the stations for each battalion in the regiment and combats by year, as well as short biographical information on the officers of the regiment. Unfortunately, there isn't a similar page for the 66th Regiment
Ackroyd, Marcus. Advancing with the Army: Medicine, the Professions, and Social Mobility in the British Isles, 1790-1850. Oxford: Oxford UP, 2006. Print.
Blanco, Richard L. Wellington's Surgeon General, Sir James McGrigor. Durham, NC: Duke UP, 1974. Print.
Cantlie, Neil. A History of the Army Medical Department. Edinburgh: Churchill Livingstone, 1974. Print.
Howard, Martin R. Wellington's Doctors: The British Army Medical Services in the Napoleonic Wars. Staplehurst: Spellmount, 2002. Print.
Kaufman, Matthew H. Surgeons at War: Medical Arrangements for the Treatment of the Sick and Wounded in the British Army during the Late 18th and 19th Centuries. Westport, CT: Greenwood, 2001. Print.
First Person Accounts
Events of a Military Life by Walter Henry - regimental surgeon to the 66th and a very amusing writer
The Journal of an Army Surgeon during the Peninsular War by Charles Boutflower - Regimental surgeon to the 40th. Interesting in particular because he is there at the same time that I have placed John Watson. Boutflower comments more on the people and societal aspects of his service, and is much snootier than Walter Henry, but it is fascinating reading.
The Autobiography of Harry Smith - If you are a Georgette Heyer fan, than you probably already know Harry Smith - he is the soldier-husband of "The Spanish Bride". Harry's writing is amusing and gives the flavour of life as a soldier during this war.