either way that's good enough for me, and I think we can be pretty certain that this is "our" William Street that links back to Over Peover via the CWGC entry.
Sphinx knows I'm a stickler for the exact, as it could still be the wrong chap, what happened to the family of 3 you posted initially ~ are you completely confident they no longer exist?
I would be grateful if Sphinx would add his comments.
Wendi 
Wendi,
You are of course absolutely right to be a stickler - assumption is the mother of disaster! I'm just being lazy and I deserve a ticking off: good research is always well-corroborated!
sphinx's trail is actually exactly the one I followed, except
sphinx has clearly seen the actual census entries where I have only been working off the free-to-view on-line indexes. However this locality sits at the confusing junction of several Sub-Districts belonging to three separate Registration Districts. Add in a large, loosely-related local clan like the Streets and you have a recipe for some real genealogical howlers - Wendi is right to insist we are rigorous here!
Anyway to begin at the beginning ...
CWGC has
Pte William STREET 5048 13/Manchesters died 25 April 1917 aged 28, son of John & Agnes STREET of Mainwaring Arms, Over Peover.
SDGW adds that he was born in
Goostrey and resided in Peover.
From this we can estimate his birth year as
1889 +/- 1 year.
A
Births search on surname "Street" with forenames containing "William" in Cheshire with that birth-year range gives the following (the locations are the
Registration Sub-Districts):
1888 William Henry STREET - Church Hulme
1889 Frederick William STREET - Runcorn
1890 John William STREET - Church Hulme
1890 William STREET - Sandbach
1890 William STREET - Stockport
There was a William Henry STREET born in 1891 in Alderley Sub-District (near to Peover & including Lower Withington), but he is outside the birth-year range.
Church Hulme is the old name for
Holmes Chapel. Holmes Chapel and Goostrey are adjacent townships about 1 mile apart. The
Registration Sub-District called
'Church Hulme' contains the following parishes: Blackden, Brereton cum Smethwick, Church Hulme, Cotton, Cranage, Davenport, Goostrey cum Barnshaw (1867-1937), Kermincham, Leese, Swettenham, Twemlow.
From this we are probably safe to infer Pte Street is either William Henry Street b.1888, or John William Street b.1889 since Goostrey is in the 'Church Hulme' sub-district.
An 1891 Census search in Sub-District "Church Hulme" on Surname "Street", forenames "John", "Agnes" OR "William" brings back:
John STREET;33yrs
Agnes STREET; 32yrs
William STREET; 3yrs
there was no John William STREET or John STREET in the age range 2-5yrs.
NB I am only using the indexes here on
www.1901censusonline.com and these are specific hits on only those search terms -
this is not returning a Household. I think
I have misled Wendi here into thinking there was a family of three. My search would not find any other Surname "Street" with different forenames, and 1901censusonline has no free-to-use facility to view the data by Household and FreeCEN has hardly started transcribing the 1891 data for Cheshire
Even worse, 1901censusonline has the forename field as mandatory, so you cannot get all the Street surnames without knowing the forenames as well
In other words, using this method
I would not find any of William's siblings unless I already knew their names. Also my method does not even confirm John, Agnes and William are actually in the same Household.
On the other hand, it looks like
sphinx has had sight of the actual census return as he knows they're all in a single household in
Twemlow Green probably with some children in addition to William. He also knows that father John is a Butler. Twemlow is in the '
Church Hulme' Registration Sub-District, so these will be the same Streets that I found.
BTW I don't think the household is No 16, Twemlow Green. I think it is just the 16th household in the Schedule for the hamlet - the number is a sequence number within the census, not a number in the house address.
It would be good to get this 1891 data confirmed by someone with access to the full census returns before we go further, as the next step takes us onto the 1901 Census and moves to Lower Withington, home of several sets of Streets, who all seem to be loosely connected with brick selling and bricklaying. Lower Withington is in the Alderley Registration Sub-district and we already know there was another William Henry STREET of very nearly the same age in that Sub-district in 1891, so I think we need to move
very carefully 
Wendi/sphinx can you confirm the 1891 data on ancestry.co.uk?Cheers,
Mark
