Sonia Tomic (ST): We’ve worked with Simon on quite a few projects now. We were introduced through our retail work for Selfridges and from there it expanded to collaborating on the Fortnum & Mason Royal Exchange, as well as our own kitchen at Universal Design Studio and the San Carlo Bottega champagne bar, also at Selfridges. They’re all pretty diverse projects but we turned to Simon to create a warm, human focus in each of them. His lighting gives that handcrafted touch that encourages people to gather round, like a campfire.

Simon Day (SD): Universal come to me with beautifully rendered designs and they have a clear idea of how they want one of my pieces to fit into the scheme. But what I love is how open they are to material experimentation and to the process of translating that design into a material object. They may have specified polished brass, for example, but then there are many types of brass to choose from and questions like ‘do we keep an edge on it?’, etcetera. There are so many tiny decisions in the making process that change the feel of a piece.

ST: Yes, it’s that level of detail in the exploration of materials and technique that’s so exciting when working with collaborators, because although we’re architects and designers we’re not necessarily craftspeople – so working with specialists like Simon means you get introduced to other practices and new materials, finishes or processes that we might not be aware of. It’s just so enriching, for me personally but also for a project. It means that things can develop way beyond the place you would have taken them working alone, just because you’re working with new ideas and new materials. Simon acts as that connector point for us.

SD: I like that idea of being a point of connection, and I think that’s how I’ve always tried to work really. So, again, with the San Carlo lamps the Universal team gave me the designs and then I went away and made some rough prototypes to test out materials, but at the same time I was also consulting other craftspeople like our metal spinner, Jim – who’s been doing it for fifty years – and asking what his approach would be, so already you’ve got this really collaborative process of different specialists working together to solve the problem. I could try to learn how to spin metal and take it in-house, but I don’t feel I need to do that because I really enjoy and respect working with specialists.

ST: I often see Simon as the guardian of the design. And that’s the major difference between working with a collaborator versus a contractor. A contractor is just about execution of the design and doesn’t add a layer of assessment, whereas a collaborator really brings that expertise to bear on a project.

SD: A lot of this just comes down to how you enjoy working, doesn’t it? There are moments when you have to stand back and take stock and remind yourself why you’re doing something. For me this kind of process is just very satisfying, where you know you’ve worked hard to make something the best that it can be, right up to the final install, and then the moment when you can see people interacting with it. One of my lights might just be a small part of a huge and complicated design, but I want it to be doing the best job it can.

ST: You say your lights are one small part, but I’d disagree with that – they’re essential details that bring the whole thing to life. I don’t think it’s possible to capture the impact of these handcrafted details with photography; it’s something you just have to experience physically in the space, and you can see what a difference it makes to people when they’re in these spaces. A lamp may seem small when you compare it with a 10-metre (32¾-foot) bar counter, but I’m obsessional about holding on to these details because they’re what give the final project heart.