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I reckon this is the marriage?

September qtr 1869
Derby    Vol 7b, Page 621

Richardson, Joseph
+ and on the same page +
Handley, Annie


And therefore, this is them in 1871:

Reference RG10, Piece 3561, Folio 112, Page 2
Elm Street, St Alkmund, Derby

Richardson, Joseph  Head  M  22  Tailor  b Stapleford, Nottinghamshire
Richardson, Annie  Wife  F  20  Dress Maker  b Derby


And in 1881:
Reference RG11, 3405, 124, 15
20 Parker Street, St Akmund, Derby

Richardson, Joseph Atkin  Head  M  32  Master Tailor  b Stapleford, Nottinghamshire
Richardson, Anne  Wife  F  30  b Derby
Richardson, Joseph Edwin  Son  M  8  b Derby  Blind
Richardson, Annie May  Daughter  F  6  b Derby
Richardson, Eleline Mary  Dayghter  F  4  b Derby

FindMyPast has information about gaps in the censuses.
www <dot> findmypast <dot> co <dot> uk/helpadvice/knowledge-base/census/index.jsp#issues

Gaps in 1851 appear in Cambridgeshire/Suffolk, Essex, and Dorset.

But Dudley appears to be OK.

With enumerators and transcribers all being known to get things wrong, you might need to use a little lateral thinking! 

Or tell us who you are looking for, and maybe one of us can find your people?

Marriage:

December qtr 1872
Barnsley  Vol 9c, page 231

Green, Henry
Hardcastle, Ellen

Found a Lucy May with her grandparents in 1891 - if that's any help?

Reference RG12, Piece 895, Folio 42, Page 22
7 South Street, Ventnor, Isle of Wight

Russell, George Henry  Head  50  Cab Proprietor  b ST Lawrence, IOW
Russell, Elizabeth  Wife  F  48  b Withington, Herefordshire
Russell, Charles William  Son  M  16  Driver  b Ventnor
Russell, Edwin Arthur  Son  M  11  b Ventnor
Russell, Lucy May  Granddaughter  F  4  b Ventnor

I use FindMyPast and simply select Census Reference Search.

In Ancestry, go to Search and click on "Go To Old Search" (somewhere top right).
Select the relevant census, and towards the bottom of the search box, you'll find a section allowing you to enter the reference numbers.