Reed cutting
Reeds have to be cut every few years or the reedbed will dry up and become overgrown.
Years ago the cutting of reed provided jobs during the winter, either for farm labourers who could not work the land in winter, or for thatchers themselves, who could, of course, not carry out their trade during the winter months. You would not like your house to have no roof in the middle of winter would you!
Reeds used to be cut by hand using scythes but this was very hard work. Nowadays special mowers are used but the reeds are still bundled up by hand. Sometimes a special reed-cutting boat with caterpillar tracks is used, but this is expensive to hire.
There's lots more about reed cutting at norfolkreed.co.uk.