Thanks for your post - sorry for the delay in replying.
Your first data set regarding my grandfather exactly matches the result I got way back from an alternative genealogy site.
The 1870 US census result also looks promising - despite the name being shown as Elizb Spencer.
All bar one of the UK records I have found for my great-grandfather's 'wife' show her as Sarah Elizabeth (Hirst). The birth certificates of her 3 youngest children show her maiden name to have been Spence.
However, her 2nd son William Ashton Hirst's birth certificate show her simply as Elizabeth (Hirst), formerly Spence (or Spencer - the handwriting is not 100% clear!)
Hopefully, a marriage certificate with sufficient details will eventually come to light in order to confirm [Sarah] Elizabeth's origins.