May just be a coincidence because location is not where I expected.
Ancestry has baptisms for Elizabeth Sykes and Mary Ann Sykes on 9 Nov 1831 at Woolwich. It is noted that Elizabeth was born on 22 Aug 1828 and Mary Ann born on 29 Nov (1831), parents Richard and Elizabeth, his occupation sailor, abode Rope yard Rails.
The family should be in Greenhithe at this time, but that's only about 13 miles from Woolwich, but it does seem a good fit otherwise.