This Matthew FOURRO b.1843 may have been the son of James (d.Oct 1848) and Mary Ann (d.Jul 1848), and may have been the elder sibling of James (b. 12Mar1846) and Elizabeth Ann (b.11dec1847}. This James and Mary Anne FOURRO lived in Bethnal Green, and the two children James and Elizabeth Ann were born in Bethnal Green.
In his turn, James FOURRO (d.1848) may have been the son of Matthew FOURRO and Elizabeth (nee WILLIAMS), m. 20Jul1817 in Stepney which is only 1.5km south of Bethnal Green. Assuming their children (if any) would have then been born in the 1817-1830 timeframe, a son could have been born abt. 1818, making him abt. 25 at the time of the younger Matthew's birth, 28 and 29 at births of the younger James and Elizabeth Ann's births, so this James certainly fits the time and place required of the younger Matthew's father.
It seems that GFather Matthew must have died before 1830, as GMother Elizabeth married George DOWNER on 6Jun1830 in Whitechapel, still in this same area of East London. This George DOWNER appears to have died before the 1851 census. This could explain why a 7-y.o. Matthew was living with his GMother Elizabeth DOWNER at 42 Edward Street in Mile End Old Town at the time of the 1851 Census. Perhaps the younger James and ELizabeth Ann died as infants following the death of their mother Mary Ann in 1848?
The high number of family deaths at early ages conforms with the general low life expectancy around the East End of London in the early to middle 1800's before the major civil engineering works of the latter part of the 19th C. which provided relatively clean water supplies and comprehensive, effective sewers to this and other urban areas of London. There was a major cholera epidemic in 1832 which claimed over 800 lives in the east End alone. A second epidemic peaked in 1848/49, said to have claimed more lives than the first, a total of over 55,000 in England as a whole. Further outbreaks followed in the 1850's up until the last major outbreak in 1866 which was largely confined to the areas of East London not yet on the new sewer network.
Any input to or criticism of these speculations is most welcome!