Vivien:
I checked the 1881 census and there were three Leonards who were possible ancestors of yours and the father of Gertrude: Leonard#1 born 1841 and lived on King St. He was a fisherman. Leonard #2 his son born 1861 also a fisherman. Leonard #3 born 1848 living London Road. Leonard #4 his son born 1880. There was no Gertrude: presumably she was born after 1881.
I have a very large file on the Worcester Darkes with many lines researched.(back to 1630) Interesting to note that the name "Williams" crops up often. I have one branch that might connect: John Darke married Sarah Williams and had twins: Leonard and William Williams. William Williams had a daughter Ann Bell Darke. She married a Samuel Osborne and in 1881 they lived on Wyldes Lane.
If you want to go further with your research, I could send you a file or snail a family tree to you. I would like more data on your grand parents eg. name of Leonard's wife.
Regards, Maurice