Hi Slipper
I have just caught up on all the new information, so no mention of a Mawby on the certificate 

 How about an address does that tie in with any census info you have?
Interesting the mention of a Sarah Burton though as I had come across this ............... 
1851 H0107 2069 137 29 - Civil Parish Long Lawford - Address Lawford Hill 
Transcribed as Kurton but I think it looks like Burton
Sarah Burton Head Widow 57 Long Lawford - Field Woman
Elizabeth 
Clark daugh  unmar 25 Long Lawford - at home
there is an Elizabeth Clark 15 living just above Elizabeth Mawby in 1841 ............... I wonder, could she be the same girl? 
And an Elizabeth Clarke Servant in Newbold on Avon on the 14 Sept 1851 baptized her son a John 
Frederick  Clarke
Maybe this could be Sarah Burton in 1841 not far from the Mawby family .............
Susannah Burton 68 Carpenters Widow
/
Sarah Burton 44 Carpenters Widow 
James 9
Emma 7 
All born in County 
And to add I also came across this which I thought worthy of a mention ..................
Marriage of a William Burton Bachelor and Sarah Clarke Spinster in the Parish of St Michael Coventry 29 July 1832 both of this Parish (although if I remember this correctly they would only need to be there for abt 3wks to make this claim) married by Banns - Witnesses Wm Bird? and 
Mary ClarkeForgive me if you have this already but as I mentioned earlier I do love a good puzzle 

All the very best
Z