Susannah Rush
1891 census: Langeglos, Camelford reg dist, aged 12, mother Elizabeth, widow
(2 miles from Michaelstow)
baptised 01 Oct 1879, Lanteglos by Camelford, parents George and Elizabeth Jane, father quarryman
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=2161602was very young when she had a child (if she was this mother):
Elizabeth Ann Rush, baptised 02 August 1891, Michaelstow, mother Susan, residence Langeglos, no father's name but occupation labourer
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=1953554On 18 August 1895 at Michaelstow, Susannah Rush married Richard Cowling; he was 22 and she was 18, but that was a lie: she was not yet 16; witnesses were Matthew Rush (her older brother) and Ellen Rush; she was daughter of George, a labourer, and resident at Trenewth
http://www.cornwall-opc-database.org/search-database/more-info/?t=marriages&id=770979In 1901 in St Teath, they are:
Richard Cowling 27, slate quarryman
Susanna 22 (in fact 21)
Richard R 5
Flossy I 3
The two children's baptisms:
Richard Ronald at Michaelstow 05 April 1896, mother Susan, father Richard, labourer
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=1953563Flossie Irene at St Teath 26 April 1897, mother Susanna, father Richard, quarryman
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=958416Elizabeth Ann Rush's birth was registered June quarter 1891 at Camelford.
There is no further record of her (marriage, death) in Cornwall.
In 1901 there is this household in Lanteglos:
Samuel Rush 29, slate quarryman
Susan 30
Elizabeth 9
Mary Jane 8
John Robert 6
Richard H 4
William James 3
Samuel Rush was the son of John and Elizabeth of Langeglos.
Samuel Rush and Susan Smith married June quarter 1891, Camelford.
There are two baptisms for them at the OPC site: Harold 1900 and Loveday 1904, but not the older children.
There is no other birth or baptism of an Elizabeth Rush c1892.
Now, the other possibility is that Susan Smith, by then married to Samuel Rush, was the mother of Elizabeth Ann Rush 1891. It would seem odd that her husband was not named on the baptism record, if so, and that the father was called a labourer (but the usual entry "single woman" was not made).
Susanna Rush Cowling (born in Lanteglos c1879) and Richard are still in St Teath in 1911, with one more child, Leonard. Susannah Cowling died in 1940 in Camelford reg dist.
Susan Smith Rush (borne in Michaelstow c1869) and Samuel are in Lanteglos with numerous children. Susan Rush died in 1962 in Camelford reg dist.
I had originally thought Susannah Rush Cowling the more likely candidate to be the mother of Elizabeth Ann, but perhaps Susan Smith Rush makes more sense.
On the other hand, your Lilian naming her first child Richard might point to Richard Cowling, husband of Susannah Rush Cowling, being her father or stepfather (but for some reason she was reared by the other Rush couple, who were presumably related anyway, and would have been just married when Elizabeth Ann Rush was born to the very young Susannah Rush, if that was the case). The birth certificate itself, for Elizabeth Ann Rush, might clarify this.
In any event, I think this Elizabeth Ann Rush is very likely your Lilian.
It will be very interesting to see whether Lilian named a father on her marriage to Mr Warren, and what she said her marital status was.
btw, in case we haven't done it, George Henry Evans's 1886 baptism is here:
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=1641988(and the baptisms of Alice Maud and Richard Henry Charles are there as well)
edit -
There are 7 famiy trees at Mundia/ancestry showing Samuel Rush, most of which show Elizabeth Ann Rush, but with no info about her beyond her census age from 1901 (for some reason, searching for Elizabeth herself brings up no results).
Susannah Rush is in one or two trees, but the only information is her birth.