Here's your grandparents Marriage Index entry - you may need to order a certificate to show their ages & Fathers names
Marriages Jun 1928
FRANCIS Violet to STORRY Chelmsford 4a 1513
FRENCH Ada LESTER Chelmsford 4a 1513
Lester George S E French Chelmsford 4a 1513
Storry Ernest H to Francis Chelmsford 4a 1513
and Violet's - BUT, there are multiple candidates born in Essex overall, altho the majority have more than one forename ... this does look good tho being 'of an age' and CHELMSFORD
Births Dec 1905
Francis Violet Chelmsford 4a 664
I would agree that Violet's birth 1905 looks good

Use the free search 1911 census
http://www.1911census.co.ukFRANCIS Violet Chelmsford then search again with
FRANCIS Chelmsford other members of household Violet
as mentioned to view original transcript you need to purchase credits
The following would appear to be Violet's parents
as suggested ordering marriage certificate would confirm
James FRANCIS name on same page
Minnie WRIGHT
1896 Dec q Chelmsford
1901c George Street, Chelmsford, Moulsham Essex
RG13 Piece:1672 Folio:27 Page:16
FRANCIS, James Head Married M 27 1874 Laborer At Arc Works Kelvedon Essex
Minnie Wife Married F 26 1875 Great Samford Essex James Sydney Son M 4 1897 Great Samford
Elizabeth Daughter F 1 1900 Great Samford
HIGGENS, Charles J Boarder Single M 23 1878 Appleby Lincoln
Electrical Engineer Wireless Telegraph
DEAN, William Visitor Married M 24 1877 Journeyman Carpenter Cheltenham
1891c Brockel Lane, Kelvedon
RG12 Piece:1424 Folio:6 Page:3
FRANCIS, James Head Married M 44 1847 Agricultural Labourer Ardleigh
Amelia Wife Married F 49 1842 Stoke by Nayland Essex
James Son Single M 17 1874 Gardener Kelvedon Essex Elizabeth Daughter F 14 1877 General Servant Kelvedon
William Son M 12 1879 Scholar Kelvedon Essex
1891c The Street, Danbury, Bienacre
RG12 Piece:1389 Folio:140 Page:3
HAY, Edward F Head Single M 41 1850 Curate Of Danbury Little Warley
SMITH, Georgina A Servant Widow F 63 1828 Housekeeper Domestic Servant
WRIGHT, Minnie Servant Single F 16 1875 General Domestic Servant Gt. Sampford1881 census free to view
http://www.familysearch.org/Eng/Search/frameset_search.asp?PAGE=census/search_census.asp1881c Street, Great Sampford
Minnie WRIGHT age 7 Sampford Essex with family parents names are Thomas 1834 & Elizabeth 1837, William, Edward, Herbert, Sidney & Mary