We admit defeat! Ken attached a wire mesh to the corner where the martins made their nest last year, but they just moved about 1.5m to the left and tried again. After several days of watching their distress every time we hosed the site, we didn't have the heart to continue. They resumed their nest-building this evening. (They have ignored the new nest box.)

29/05: Two little birds snuggled together in their half-finished nest