When this card came up for sale on ebay I brought it because I was interested in the photographer, Fred Downer, of Watford. In particular it had a name so this could help me to date the card, and perhaps add to my knowledge of the photographer's work.
It looked a pretty straight-forward item to put online as the 1890 trade directory told me that William Arthur Stradling was a surgeon living in Station Road, Watford, and he was listed with his family in the 1891 census - but not the 1881 or 1901 censuses. All I need to do is check up on his date of death and I had got him recorded.
A quick check on FreeBMD told me he died in London in 1902 and I could have left it there - but it would only take a few minutes to check the British Newspaper Archive ... ...
What I found meant I wanted to find more - and I was hooked ...