Hi Kio
It is never a good sign when you don't get a fast reply on this site

I couldn't find a Thomas Oakley to fit the information you give. The only Thomas born Powick 1850-54 are Chance/Dance/Gwilham/Packley/Bishop/Hughes/Meddins/Sleeter. Only Packley looks anything like Oakley - see later.
I did find the following family in Powick in 1861
Powick
Ridgeway Cottage
William Oakley,head,m,34,agriculture labourer,Mather(?),Worcs
Elizabeth ditto,wife,29,gloveress,Powick,Worcs
James ditto,son,7,scholar,St Johns,Worcs
Mary Ann ditto,dau,5,scholar,St Peters,Worcs
Eliza ditto,dau,3,Powick,Worcs
Emma ditto,dau,10m,Powick,Worcs
RG9/2097 folio 93 page 16
Also in Powick is a Thomas Oakley, 27,ag lab,born Cradley,Herefordshire. He is lodging somewhere.
1871 has same Oakley family
Worcester
3 Powells Row
William Ockley,head,m,50,labourer,Herefordshire,Cradley
Elizabeth ditto,38,charwoman,Worcs,Powick
Emma ditto,dau,10,nurse,Worcs,Powick
Alice ditto,dau,8,scholar,ditto
William ditto,son,6,ditto,ditto
Roseanna ditto,dau,3,ditto,ditto
RG10/3047 folio 43 page 27
(Eliza is a housemaid in Worcester too).
Some of these children are in the IGI (James,Roseanna and Emma9 and there is a marriage William Oakly to Elizabeth Blackwell 19 Nov 1855 at Whittington,Worcs. This marriage is on FBMD Dec qtr 1855 at Pershore.
Now for the iffy bit.
1841
Powick
Richard Blackwell,36,labourer,y
Mary Blackwell,32,y
Elizth Blackwell,9,y
Mary Pritchard,1,y
HO107/1206/1 folio 19 page 2
1851
Powick
Blackwell Richard,head,50,labourer,Powick
ditto Mary,wife,40,Bishampton
ditto,Elizabeth,dau,20,Luckley (?)
Pritchard Mary,visitor,12,Powick
HO107/2043 folio 27 page 14
1861
Powick
Richard Blackwell,head,m,58,ag lab,Worcs,Powick
Mary ditto,wife,m,50,Worcs,Bickhampton
Mary Ann Pritchett,boarder,unm,21,leather glove maker,Worcs,Powick
Thomas Packley ditto,9,Worcs,Powick
RG9/2097 folio 78 page 21
1871
Powick
Richard Blackwill,head,m,68,ag lab,Worcs,Powick
Mary ditto,wife,m,59,Worcs,Bishampton
Thomas Oakley,granson,unm,19,Worcs,Powick.
RG10/3055 folio 80 page 11
Now, I have to say that Ancestry has Thomas down as Bakley but I think it probably says oakley. The 1861 entry certainly says Packley but that could be a mistranscription when the Enumerator copied out his forms.
I hope you get a second opinion on this. I can't find a birth for Thomas under either Oakley or Blackwell so it is all a bit wide open still. It might help if you can get Thomas's father from his wedding certificate.