Can't help with the marriage entry, other than what you know from the IGI - that Mary Litchfield was 29 and her father was William Kempson, so was probably a widow, and that Nathaniel was 33, father Henry.
I do know something about the Litchfields in Beds though.
Mary Kempson' s first husband was Samuel Litchfield whom she married at Houghton Conquest on 21 July 1861. He was baptised at Ampthill on 16 Nov 1834, born 2 Oct 1834, the son of William and Elizabeth. In the 1861 census he was a visitor at his future in laws, age 26 b Ampthill. It was a short lived marriage as Samuel appears to have died in the March quarter 1862, and was buried age 27 at Houghton Conquest on 13 March 1862.
But looking at your interests, it's probably Nathaniel you're interested in, not the Litchfields! In 1851 in Witton, Lancs there's a Henry Edleston widower 55 b Ramsgreave Lancs, Nichlas Edleston son 19 b Blackburn, and Nathanall Edelston son 16 b Blackburn, which is the only Henry/Nathaniel combination I can find. But if it's the right family, what was he doing venturing south to marry?
This explains why I can't find her in subsequent censuses. Mary Edleston age 30 buried at Houghton Conquest on 29 Jun 1867. Another brief marriage.
David
