Spring lambs are that year's lambs, coming in to a market which has hitherto been selling hoggs (last year's lambs) since Christmas.
Farmers who lamb early indoors can have their first lambs ready for the spring lamb trade in March, or even earlier in some counties. Up here in north Cumbria the spring lamb trade starts in April, and is just a very few lambs until later on in May when the first of the outdoor-born lambs start to appear in the mart.
We usually have a few early single lambs ready in May, at 12-14 weeks old. They'll have been born and reared outside, born in February or occasionally late January. The bulk of our lambs are born in March, and are still ahead of the majority of the hill and moorland lambs to get to the fat mart.
We've been known to get £100-£120 a head for spring lambs in May. Lambs of the same breeding will fetch £85-£95 later in the season.