You're doing some good work there, and are obviously much better at it than I am!
I'll log all of the information in my GR tree so that I can keep track of the Cooper siblings of Ethel, as I'm sure all of your research will lead me nearer to finding her.
The chronology of the Cooper and Gardner intertwining is thus;
In 1921 Ethel was married to John Bain Gardner in Edinburgh and strangely gave her usual residence as 23 The Square, Penicuik, the home as it turns out, of a James Bain, who could have been JBG's uncle, though there's no record of him having one such named. John's mum was Agnes Bain.
They married after my grandmother died in childbirth, and Ethel took my 5 year old mum under her care in Peaslake or thereabouts and raised her as her own.
This according to family stories from late mum is how things progressed;
Ethel had been in service and later had nursing training, which we assume was for the war effort, and had helped nurse my grandad back to health after one of his spells or recuperation from his injuries in France during WW1, in a house given over for the purpose for the duration of the war. Where this was is unclear, but Ethel's last workplace and residence we have records of would be Hound House.. (Oh to have paid more attention when I was wee!!)
Upon demobilisation John Gardner was offered work by the house owner but returned home to Scotland and his wife and family, but his wife Jane Dick died in early 1920 during childbirth as did the unfortunate child, and that and the fact that his injuries made work in the mines very difficult, prompted him to take up the offer and he met up again with Ethel by letter (probably to arrange his job), married her a year later and moved with my mum, who was then 5 years old and the bairn of the family, to Surrey.
The bare facts of this point to John and Ethel forming a close relationship while he was recuperating I'd guess, and her Penicuik address might have been a convenient place for her to stay prior to her marriage in nearby Edinburgh.
Mum's siblings stayed here in Scotland as they were older and all had their futures here.
My mum lived and worked with Ethel and her dad in the area around Peaslake, though she often mentioned walking on the common at Wimbledon, Epsom, and visiting Brighton and Hove with her employers who may have had a house there, and stayed south of the border until she was a teenager, though she returned home to Scotland for holidays with the family travelling from Leith by ship to sail into the Thames. She moved back up here, aged we think around 16, meeting my dad and eventually marrying and staying here.
We have no recall of her travelling down to England during the war years when we think John Gardner may have died, and my sister and brother cannot ever remember her being away from home then, or in the 'fifties when Ethel could have died, so it may be that Ethel's visit up here in Scotland when my mum was ill after losing twins in childbirth coincided with John Gardner's death. She loved Ethel dearly, and it seems inconceivable that she would have missed the funeral, but was she informed?...............
We know that my uncle, mum's brother, and his wife kept contact with Ethel, hence a cousin having memories of Ethel and the photographs.
Another part of the mystery is this;
I traced a photograph of a grave in Putney Vale Cemetery and the image was kindly sent by charles.sale at gravesphotos.com and this shows the following;
"John Gardner, died 9th Sept. 1943 aged 63 and Lilian Gardner, died 1st April 1956, aged 79"
Had my mum known of or seen the gravestone she would surely have pointed out the error (assuming we're looking at the correct gravestone), and surely whoever paid for the headstone would have noticed?
So, surely, would her remaining family...............
There's no memory of any story that JBG married any Lilian, but we have Ethel and Lilian as sisters, listed on the same census under different names and living where they did, which seems correct for each of them.
There is another Cooper family living in Shere, cousins all in the likely event, and I think I've managed to separate which lot is which so I don't think I have any errors, and as you see there are ample pointers to say which Cooper is which.
If only the English death records gave parents names I could pinpoint John Gardner, Ethel and Lilian's parents, which would prove or disprove the error, or not, on the gravestone. Of course, this grave could be of another unrelated John Gardner............
I've been pondering all this for some time now, hence my post here looking for help, advice or suggestions, and as I'm getting older I feel it's time to sort it all out before its too late and get down there and pay my respects to the people who so shaped the pattern of my mum's life, and mine.