I invested in a "woodcrete" nesting box and stuck it in a nice inaccessible spot on the side of the house where my son can see it from his bedroom, and the blue tits are starting to look interested (fingers crossed)... I have been putting out "raw" wool in a spiral feeder which previously held a fat ball, and that seemed to go quite well (blue tits, great tits and, almost miraculously round here, a couple of sparrows took it away), and I experimented by putting out some cat fur combings (our cat is a fat and fluffy beast which seems to have no interest in birds at all, which suits me fine - on Saturday, I saw him sitting on the garden table while a blackbird looked for food underneath the table, and not a twitch from him). Remarkably (or maybe not - very nice soft fur!), that was very popular, so Moggy is getting the luxury of daily deep combing so I can put out more fur for the birds! I was a bit surprised that the birds didn't make the association with a predator. Maybe they don't operate by smell?