Sorry for the delay in getting back to this - my health is very variable and some days my brain function isn't up to writing replies.
I can't find the 1854 one now, either.
I've had it for some time (Mar qr 1854 Ipswich 4a 523) and it fit with Matilda's children - her first two were registered with her surname but the third, Frederick James, born 7 Jan 1854 was registered and baptised with the Poppy surname.
Frederick was followed by William, Henry and Matilda - all registered with the surname Poppy. All were born before the 1859 marriage.