For years protecting my brassicas from cabbage white and pigeons has been a Heath Robinson affair. The last two seasons have been a complete write-off. I bit the bullet a few weeks ago and purchased a 3 × 1.5 x 1.5m vegetable cage. I'm very pleased with it.
Yes, utterly uneconomic, the cost would probably keep me in brassicas for ten years. But my allotment is for taste and pleasure, it's not about money. The other factor was two years of losing important, to me, crops was dispiriting and very demotivating. If there's one thing an allotment grower needs it's motivation.