Hi catterbug! Welcome to the Welsummer thread!
Welsummers are not known to go broody, but on occassion someone is lucky enough to experience it. I have heard that they tend to not make good mothers, but then again, some have said that their broody Wellies did make good mothers. I think it really all boils down to the individual bird, no matter the breed, even in breeds that are known for their broodiness, mothering abilities and frequency, gets birds that do just the opposite and never go broody and do not make good mothers.
I have never had a Welsummer hen go broody or even try....but a couple who bought hatching eggs from me had 4 of the pullets they hatched out lay a few eggs then go broody, they were not amused to say the least as they purchased these birds because they are not prone to going broody. They also said that the girls were so determined that the only thing to do was let them sit it out and hatch chicks. Last report was that they raised the chicks just fine until about 3 weeks then lost interest, so the couple ended up brooding the chicks until they were old enough to go outside. They also sold the 4 hens that went broody.