I was focussing on the 1911 John James death because in the 1911 census, they are only listing one John James, born in Aberthaw in 1837, and he is listed as a lodger and old age pensioner, which didn't make a great deal of sense to me (on Union Street, as I remember).

Mary Ann was at Box Tree Cottage at the time as a "visitor" (but is listed as married not as a widow), so I suppose he could have been elsewhere as well. Only five years later, she also left a much more substantial estate (approximately four or five times larger) . . . If one spouse is remaining, does that mean that they only include personal property, rather than real property in the estate? (Might account for the difference.) By all accounts she was a fairly successful businesswoman . . . but I can't see her accumulating so much so quickly (toward the end of her life), and I am making the unwarranted assumption that a woman's assets were joint with her husband's even if she were the one who acquired them . . .

Of course, her mother died in the interim, so there might have been an inheritance during that time as well, but with several siblings I wouldn't have expected that to be susbtantial.

The 1913 death makes sense, though, as the chances of two seventy-six year old men sharing the same name, born in the same small town, both living in Cardiff and leaving a widow named Mary Ann seem a bit improbable. (I think the 1911 census was where I went astray . . .)

"Your" Bridge Street is almost certainly in the City Centre Parish of St John i.e. not out in the Llandaff suburb.

http://sites.google.com/site/stjohnscityparishcardiff/parish-history

Bridge Street {Heol Y Bont in Welsh} in the region of the Castle and St Mary's St has a post code of CF10 xxx....

There has been a fair amount of re-development in the area so houses have been pulled down and I suspect numbering is not what it was 100 years ago...

http://maps.google.co.uk/maps?hl=en&safe=off&rlz=1T4ADBF_en-GBGB310GB310&q=...

probable BMD for John James born Aberthaw:-

Name: John James
Estimated birth year: abt 1837
Year of Registration: 1913
Quarter of Registration: Oct-Nov-Dec
Age at Death: 76
District: Cardiff (1837-1974)
County: Glamorgan, Monmouthshire
Volume: 11a
Page: 379

Probate Index

Name: John James
Probate Date: 20 Jan 1914
Death Date: 19 Nov 1913
Death Place: Cardiff, Wales
Registry: Llandaff

James, John of 8 Planet St Cardiff died 19 November 1913
Probate Llandaff 20 January to Mary Ann James widow
Effects £99 1s 9d

Planet Street is at the back of the old Cardiff Infirmary , say 300 - 400 yards east of Bridge Street.

http://maps.google.co.uk/maps?hl=en&safe=off&rlz=1T4ADBF_en-GBGB310GB310&wr...

Along with the other family lore, in between living in Blakeney aka Blakeney Hill and aka Old Funace Bottom, and Trevethin/Garndiffaith (and apparently Aberdare, according to her (first) wedding certificate from Viney Hill), my great grandfather built her a house in Cardiff (apparently on Bridge Street. I thought in Castle, but it could have been Cathays . . .I don't know Cardiff very well.) I know that at some point she owned a stationary shop in St. Mary Street, and played the organ at the church.

Her wedding certificate arrived from the GRO today, listing her address at 22 Bridge Street, and her second husband, John James' address as 31 Bridge Street, both in the Parish of St. John Baptist (sic), Cardiff.

For the address, Google maps shows two possibilities; one a modernish building in the city centre, and a second a series of row houses approaching the Cardiff Road. There's a number 22, but no 31 . . . I believe that street is in Llandaff.

Does anyone have sufficient knowledge of Cardiff to offer me any guidance on this issue?

Of interest, but no real import, is that after their marriage John James becomes a stationer, which made a certain amount of sense, while his marriage certificate and family lore list him as a ship's rigger. The surprise is that on the marriage certificate she signed, he marked. Doesn't seem to make much sense for a stationer.

I believe John James passed away in 1911 (BMD indices offer two possibilites; 1911 and 1913)but the probate index for 1911 appears to be missing from ancestry.uk . . .