Dyke Stone Walling is one Scottish-born amateur's notebook on building walls without mortar, kept while learning the Catalan way of doing it on weekends outside Barcelona and comparing it, stone by stone, with the way I was first taught at home.

I grew up in the south-west of Scotland, where field dykes run over every hill, and spent two summers as a student carrying stone for an old waller who rebuilt them for farms. I moved to Barcelona for work in 2019 and assumed I had left all that behind, until a walk in the vineyard hills west of the city took me past a terrace wall that had slumped into the path and a round stone hut with a roof made of nothing but stone. I have been going back ever since.

Most weekends between October and May I spend a day with one of the volunteer groups that repair terraces and huts in the countryside, usually a train and a lift away from the city. The work is unpaid, the tools are shared and the stone is whatever the hillside offers. I am the only Scot in any of the groups and the question I get asked most often is why a wall in Catalonia and a dyke in Galloway lean the way they do. This notebook is my attempt at an answer.

Nothing here is professional advice, and nobody should rebuild a terrace that holds up a vineyard or a path on the strength of a hobbyist's notes. I do not name the groups, the landowners or the people who taught me, and I describe places no more precisely than a valley or a district. Where I use a Catalan word I give the one I heard on the hillside, which is not always the one in the books.