I'd go further and suggest that choruses as found in pop songs are also mostly uncharacteristic of British folk song.

There are lots of traditional songs that have simple refrains or burdens, often consisting of a few nonsense words run together at the end of each verse. There are some folk songs which simply repeat one of the verses as a chorus, with the same melody as the other verses. There are quite a few where the last line or couplet of each verse is repeated. But although there are some songs that do have a full-blown chorus with its own melody, they are relatively uncommon (albeit perhaps a bit over-represented in folk clubs because they are good to sing along to).