Digital composite from two 5 x 4 in transparencies, Lambda print mounted on Diasec, 100 x 50 cm (39.4 x 19.7 in), edition of 3 + 1 AP.

After the 2020 lockdown, a romantic summer trip led to the encounter with a plastic bottle washed ashore by the tide on the East Beach of Shoeburyness, on the Essex side of Thames estuary. In the studio, I photographed the bottle as I had found it: worn, crushed, encrusted with barnacles, and half-filled with slimy, brackish water.

The following week, I set off on a 346-kilometre journey on foot, tracing the river’s course from that beach to Thames Head. When I arrived two weeks later, I found little more than a dry inscription and a pile of stones marking the source. So, I continued north for another 25 kilometres to Seven Springs, which some consider the river’s “ultimate source.” Nestled in a small wood between two roads, the spring is reached via a footpath that descends a few metres to a shallow pool of clear water. A rivulet flows beneath the road through an arch in a stone wall, above which a Latin inscription translates: “This, O Father Thames, is your sevenfold source.”

I took out the bottle I had carried from Shoeburyness and poured into the spring the last few drops of water that had not leaked away along the journey. In the studio, I took another photograph of the now-empty bottle before putting it in the recycling.

Independent research has identified the Thames as one of the most plastic-polluted rivers in the world, while investigations have exposed widespread sewage discharges by water companies.