I am now back from holiday. Thank you everyone for your help, especially ....
JJen: Thank you for the 1901 information - Martha's son George Holloway Dean is only living a few doors away on the same street so this seems right. Some concerns would be that I have her death in Cardiff as 15th September 1901 living at Harriet Street and buried at St Andrew's in Cardiff rather than in Tylorstown; her birth is shown as Cardiff rather than Llanfingel; the surname gaining an extra "e" at the end is less of an issue. I have added the detail to my tree as "possible" until I check the births for Percy, Archie and Sydney.
Ladyhawk: Thank you for the 1901 information. Alfred is a new name for me. Does also seem strange that Percy and Archibald are the same age. One to explore further, especially finding the birth records. Thank you for the 1871 census - fortunately I already had a copy of this. Thank you for the clarification of UD - really useful and a lesson to me to check Genuki! Thank you for the information regarding the possible marriage between John and Elizabeth. I have found the parish transcription giving the date as 30 July 1838 (I guess just creeping into Q3), however, in the transciptions the residence is Bristol (I was expecting Malmesbury). With regards to Adolphus, on Martha's death cert is an A Emery (brother) so I think it is safe to assume that this is Adolphus.
Cath151: Thank you for the 1861 spot. This seems a probable especially given the age and birth location.
Deidre784: Thank for the information on Charles. I had the baptism (George Street) but not the Newport index reference. Thank you also for Michael's details - I already had a copy of the Death cert, will and probate. Interestingly, he dies in 1886 but probate wasn't given until 1905. Your information on Michaelston vs Llanfihangel was really useful. Thank you also for backing up the marriage although the Bristol residence gives me a small doubt.
Mabel Bagshawe: I agree, Michael certainly had his ups and downs. Quite surprising really, as his father was a very successful (and quite wealthy) pawnbroker in Bilston.
Unfortunately still not able to find Martha's birth!