Hi, ambly.
The Cooper surname is in a totally different part of my tree so I think that will just be coincidence.
Whilst your COOPER line is different, sadly, it's perhaps more unlikely than not though, that Elizabeth COOPER is not somehow related to the LANGTONS. It could be thru Elizabeth Peters, Joseph, or it could be an ex-mother-in-law even. For what it's worth, in case it's ever needed:
Between 1840 and 1852, there are two possible deaths for Elizabeth COOPER, 1843 and 1844:
Elizabeth COOPER, widow, age 73, Watling Street
Burial 21 January 1843, St Margaret's Leicester
Registered MAR Qtr 1843, Leicester
Elizabeth COOPER, widow, age 75, Metcalf Street.
Burial 7 August 1844, St Margaret's Leicester
Registered SEP Qtr 1844, Leicester
Cheers
AMBLY