Hi,
I found the Pricilla HASWELL, with the same marriage details as Allen by putting in the name Priscilla, West Indies and 1825 in the search boxes. Her result came up because she has an unusual name, but if you try with, for instance "Mary" you get 78 results to check through. It would be helpful if they included the page number in the search boxes.
I suggested getting the marriage certificate to as much discount the marriage as prove it, sometimes that is the only way to be sure.
I have found this by searching the newspapers at FindMyPast,
Surrey Comet 14 May 1870
ROYAL CAMBRIDGE ASYLUM FOR SOLDIERS' WIVES
Priscilla HEDLEY was married twice; her first husband served in the 4th Foot at Salamanca, Vittoria, St. Sebastian: also at Washington, Baltimore, New Orleans and Waterloo: Her second husband had served 23 years in the Royal Artillery, and was accidentally killed in the discharge of his duties.
I've just transcribed the part which concerns Priscilla, but now you are a member you will be able to see the full article

I think the phrase "accidentally killed in the discharge of his duties." means just in the duties of his job rather than Army duties as I also found these articles,
West Kent Guardian 02 September 1843
An Inquest was held on Monday at the Fortune of War, Woolwich on the body of Allen HEDLEY, whose accident we reported on in last week's Guardian, and who died on Sunday from the effects of the injuries he received in the neck. The Jury returned a verdict of "Accidental Death"
which although they have his first name wrong seems to refer to this frank account of a horrible accident.
West Kent Guardian 19 August 1843
WOOLWICH
Accident - In the forenoon of Wednesday last, George HEDLEY, formerly a Sergeant in the Royal Artillery, but now pensioned. and who assists in the store-keepers department in the Arsenal met with a most serious accident. Whilst one of the fatigue carts of the Royal Artillery was being loaded from the store he caught hold of the horse's head in order to back the cart, when the animal plunged forward, knocked him down, and trampled on the back part of his neck, by which several of the vertebrae were so much injured that there is no hope of his surviving.
How awful.
Just to let you know, I've found that the search function doesn't always give results in the newspaper search at FindMyPast as the transcriptions can be quite odd, for example the last article had Hedley as Iledley, I only found it by searching for the newspaper referred to in the previous article.
West Kent Guardian, August 1843, and Accident in the search box. I always try to find different ways to search the newspapers as sometimes you find new results.
So now we are looking for a widowed Priscilla who marries Allen HEDLEY. There is a chance that she didn't marry him or her first husband legally. Although I can only find half of it, this book gives an idea about women/wives and there roles in the British Army,
http://www.rootschat.com/links/01kua/Regards,
Daisy