freebmd show what may be him - Dec 1875 quarter birth, St. Olave Southwark, Richard Frederick Mitchell. (St. Olave Southwark included Bermondsey from 1870 to 1901, after which the district of St. Olave Bermondsey was created).
I think he may be listed by his middle name in 1881:
6 Melior Street, St. Olave Southwark,
RG11/555/28 page 10
Richard Mitchell, 36, Cellarman, b. Buckingham
Ellen, 36, b. Gloucestershire
Ellen, 11, b. London, Surrey, Scholar
Mary, 9, b. ", "
Frederick, 5, b. ","
John Russell, boarder, 22, b. London, Surrey, Carman
Horsleydown in 1891 there is on the index, on the same page:
Ellen Mitchell, b. abt 1845, Gloucestershire
Mary Elizabeth, b. abt 1872, Bermondsey
Richard Fred, b. abt 1876, Bermondsey
1871, RG 10/634, St. Mary Madgalene Bermondsey
1 Martin Street
Richard Mitchell, 29 Porter At A Wine Merch., Bucks Stoke Pogges
Ellen, wife, 28, Gloucestershire Cirencester
Ellen S?, dau, age obliterated by ink splodge, b. Bermondsey.
There's a possible marriage in Lambeth 1868, Richard Mitchell to Ellen Gardner (the other two on the same index reference are Peter Kreis and Amalie Schatz, who probably married each other). Richard's birth certificate would be a good option to get first, though, in case this is the wrong marriage altogether.
Richard Mitchell d. Mar 1888 quarter, St. Olave district, aged 47 - may be him. Liked to change his age around a bit, eh?