I'm at a lost when it comes to tracing the parents of Ellen Robinson, born abt 1850. 
All I know about her is that she married John Richmond in 1868. On the marriage record, she is listed as 17 years old, and living in Navigation Street, Birmingham. Her father is listed as being George Robinson, a labourer. One of the witnesses of the marriage was Mary Robinson.
I've been taking a look at the above this afternoon and wondered if witness 
Mary Robinson is related to Ellen 
might be a sister or mother There's this 1861 census entry it may have no connection to your Robinson family but thought I'd post as her father is named George and his occupation labourer. This Ellen Robinson is not on the 1871 census with her parents George & Mary 
BUT if she's only aged 7 that would make only 14 on the 1868  marriage to John Richmond  
 if incorrect at least this Ellen can be ruled out
  if incorrect at least this Ellen can be ruled outEllen’s age transcribed as 
27 on Anc*y looking at the original entry age written as 
29 crossed out and I think it looks as if 
 7 is written above.
1861c Piece 2139 Folio 80 Page number   13
address 
Communication Row      Geo Robinson   45 Head London 
occ labourer / day 
Mary Robinson   29   Wife 
Dudley WorcestershireELLEN Robinson   27   Daughter
Sarah Jane Robinson   3   Daughter
Mary Robinson   1/12   Daughter
all others born Birmingham, Plus one boarder      
1861c https://www.familysearch.org/ark:/61903/1:1:M7JG-F34?lang=en - family search 
Ellen’s age  transcribed as 3 same as her sister Sarah Jane’s  
Not found a birth or baptism for Ellen Robinson with mn Wright  

Could it be a second marriage for her father George or was she the illegitimate daughter of Mary WRIGHT 

Sisters Sarah & Mary ROBINSON’s baptism same day 
27 April 1861Sarah Jane Robinson age 3 years 
Born 20th Nov 1857Mary Esther Jane Robinson age 2 months 
Born 1 Mar 1861Baptism Place   Birmingham
Residence Place   Edgbaston
Church   Islington Methodist Church
Parish as it Appears   The Wesleyan-Methodist Chapel
Father   
George Robinson Mother   
Mary abode 
Communication RowROBINSON, SARAH  JANE   
mmn WRIGHTGRO Reference: 1857  D Quarter in BIRMINGHAM  Volume 06D  Page 63   
ROBINSON, MARY  ESTHER JANE    
mmn WRIGHTGRO Reference: 1861  J Quarter in BIRMINGHAM  Volume 06D  Page 44   
Added - Mary Esther Jane Robinson Age 2, abode St Martins Street 
            Burial 15 Feb 1863 St Bartholomew Birmingham
1871c Piece   3100 Folio   38 Page number   27
George Robinson 60 Middlesex London Head occ ??   
Mary Robinson   38 
Worcestershire Dudley   Wife
Sarah J Robinson   15   Daughter
Theresa Robinson   5   Daughter
1871c 
https://www.familysearch.org/ark:/61903/1:1:V5YH-RGN?lang=en??za Amelia Robinson Born 
24 Jun 1864Baptism    31 Jul 1864 Birmingham
Residence Place   Edgbaston, England
Church   Islington Methodist Church
Parish as it Appears   The Wesleyan-Methodist Chapel
Father   
George Robinson Mother   
Mary Original reads 
Thirza Amelia ROBINSON, THIRZA  AMELIA   
mmn WRIGHTGRO Reference: 1864  S Quarter in BIRMINGHAM  Volume 06D  Page 11   
1881c  Piece 2964Folio   70 Page number   31
George Robinson 70 London, Head occ 
Gen Labourer   Mary Robinson   47 
Dudley   Wife
Sarah J. Robinson   20   Daughter
Thearsa Robinson   15   Daughter
Charles Robinson   10   Son
Mary J. Robinson   5   Daughter
1881 c 
https://www.familysearch.org/ark:/61903/1:1:Q27N-S4ZD?lang=enIs this Mary J birth entry - no mmn
ROBINSON, MARY  ESTHER JANE    -  
GRO Reference: 1876  S Quarter in BIRMINGHAM  Volume 06D  Page 51
possible death entry for
George ROBINSON age
 79 Dec 
1889 Aston Warwickshire
There is an 1854 marriage for a George Robinson to Mary Ann Wright , 
both 
res. Tonk St., both 
single, both made their mark - image on Anc*y
27 Nov 
1854 Birmingham, St Martin, Warwickshire, England
George Robinson occ 
roadman Father John Robinson
Spouse   
Mary Ann Wrightlittleem1906 - please come back and let us know your thoughts