Some projects come together over many years; occasionally the photographer is not even aware that a project or series of pictures exists at all. But as time passes, they may look back through their work and find a common thread.
One series that has been shot over the past quarter of a century is The Kiss by Brian Harris.
Brian was a staff photographer at The Times and then chief photographer of The Independent newspaper when it launched in 1986.
Brian told me that:
"While travelling the world as a news photographer covering insurrections and politics, it was a blessed relief sometimes to just go off for a long walk with one camera and one lens looking for pure images that were gentle and kind."
And so the series was born. I asked Brian to outline his thoughts behind the collection:
"I started looking, waiting, to photograph couples kissing following the likes of Robert Doisneau and his iconic photograph taken near the Hotel de Ville in Paris.
"I enjoyed the experience of trying to capture in one or maybe two frames that moment of pure joy as a couple embraced, kissed and were oblivious to all around, including me.
"It was a way of training my eye and brain and camera to all work in harmony. I think my first really nice kiss image was made in Paris, where else? It was of a young couple sitting on a bench in the Jardin des Tuileries. They would be middle-aged now and I wonder if they are still together.
"The series now contains photographs from Italy and Malta, from Berlin and London and more recently from my home patch of Cambridge where I now live.
"I've never asked permission, it was always one-two frames taken on the wing and then I moved on. So far, no-one has ever objected and no-one has punched me on the nose - but with the awareness of photographers working on the streets by the police and the public, I suppose it is only a matter of time before someone calls foul.
"Enjoy these images for what they are at this Valentine's period: all you need is love, love, love..."