In the second week of June we carried two pieces out of the workshop and set them down in the garden: Spira and Sentinel. It was the first time either of them had been asked to work under an open sky, and we wanted to see what the light would do without walls to bounce off.

Two forms, one evening

Spira went in first, low among the grasses, where its coil catches the last of the day and holds it. Sentinel took the far corner by the stone bench, upright, patient, doing what it has always done: standing watch. As the light thinned, the garden rearranged itself around them. Hedges we have walked past for years came forward. The path to the gate turned into a decision rather than a habit.

Both pieces had been prepared for the season beforehand. Joints sealed, finishes cured a second time, cables run through conduit and buried before anyone arrived. We do that work quietly, because a lamp outside has to survive rain that comes sideways, and because nobody should have to think about it while they are standing there looking at the light.

What the garden told us

• Copper and brass behave differently after dark. The warm metals give back more than we expected, and Spira's coil reads almost as a second source.
• Sentinel needs distance. Within two metres of a wall it flattens; at the edge of the lawn it becomes a figure.
• Insects are part of the installation. We stopped counting them as a fault.

Light indoors is a room's opinion of itself. Outside, it is weather.

We had invited a handful of people: colleagues, two gardeners, a neighbour who has followed our work since our first years. Nobody left at the hour we suggested. Over the following weeks the letters arrived asking the same question, more or less, every time. Can these live outside permanently? After a summer of testing, the answer is yes, and we now make both in an outdoor version. The garden has kept them.