Hello there is a family tree on my heritage and although this information could be wrong and may need double checking, I think this could be a good basis. I'll write here what's on the tree:
Frost Side----
Ethel Mary Frost's dad was Joseph Frost Born December 5th in Buxted, Sussex. He married Celia Maria Baker in 1907 in Battle. His residence in 1911 is: 6 Roseberry Terrace, Bexhill on Sea, Sussex. Joseph Frost died in 1952, October 5th. Him and his wife had 3 children: your Ethel and Walter and Albert. Joseph Frosts' parents were James Frost and Ruth Clark(e), and his siblings were:
-Hepzibah Frost 1876-1909
-Mercy Frost (Edwards) 1878-1956
-Naomi Frost 1979-1911
-Ruth Frost (Scanlan) 1884-1963
-James Frost 1885-1913
-Samuel Frost 1887-1959
-Obed Frost 1889-1966
-Mary Kezia Frost (Pope) 1892-1980
Some interesting names here for Joseph Frosts siblings!
Joseph's father, James, was born on September 21st 1851 in Framfield, Sussex. Christened November 2nd. His occupation throughout the censuses seems to be either a farm worker or agricultural labourer. He married Ruth Clark(e) in 1875 in Hadlow Down, Sussex. James Frost died on January 28th 1913 in Uckfield, Sussex. Buried Feb 4th in Hadlow Down. James' parents were called James Frost (senior) and Henrietta Hannah Richardson.
His parents had quite a few other children and so his siblings were:
-George Frost 1850-1925
-Mary Frost 1853-1923
-Frederick Frost 1856-1917
-Emily F Frost (Streeter) 1858-1936
-Samuel Frost 1860-1940 there is a photo of him i found, reply if you want me to post it here

-John Frost 1863-???
-William Frost 1864-1914
-Henry Frost 1866-1939
-Eli Frost 1870-1949 possibly short for Elias or Elijah
-Benjamin Frost 1876-???
-David Frost 1878-1914
As you can see James' siblings had quite normal names compared to his children, and from what I can see the unique names come from his wifes (clark) side, her own siblings had names like Mahala and
Hepzibah. I can tell you more about the clark side if you want

.
James' father, James Senior Frost, was born 23rd May 1827, Mayfield, Sussex. Christened June 17th. His occupation was also an agricultural labourer. He married Henrietta Richardson on July 6th 1850, Framfield Sussex and he died on the 28th of December 1892. Buried on January 3rd 1893 in Waldon.
His own parents were called William Frost and Barbara Colbran.
They also had lots of other children so James Seniors siblings were:
-Henry Frost 1817-1891
-William Frost 1819-1880
Mary Ann Frost 1821-1841
-John Frost 1823-1825
-Barbara Frost 1825-1845
-George Frost 1829-1844
-Sarah Frost (Diplock) 1830-1905
-Benjamin Frost 1832/1833 died as a baby
-Samuel Frost 1835-1841
-Frederick Frost 1837-1838
-Eli Frost 1840-1850
-Susan Frost 1842-1911
The family tree goes back all the way on the Frost side to Richard Frost born circa 1670 in Heathfield Sussex and who died in 1727 in Heathfield, Sussex. There are a few people in between James Senior Frost and Richard Frost so I'll do a quick summary here of the direct ancestors to Ethel May Frost:
Ethel May Frost---> Joseph Frost---> James Frost---> James (senior) Frost---> William Frost---> John Frost---> John (senior) Frost---> John (senior senior) Frost---> Richard Frost
If you'd like any more detail on any specific person or on a census then please ask, most of it is on the family tree I have found, but i'd be happy to look for something for you aswell
Hope this helps!