Hi Seriousbill,
They are a breed fromone particular farm in Scotland, This guy has the permiit for the name of Black Rock, but in England there are other names, like pepperpots.
It is just the trade mark for this farm I believe.
here is some info I copied:
http://www.blackrockhens.co.uk/
Why is this chicken better than pure breeds for domestic egg production? - this is because she will lay more than any pure breeds in the UK nowadays, and she is more cost effective in terms of the amount she eats for each egg. Unlike the pure breeds who have had little consistent selection for good productivity in 90% of the current strains, Peter Siddons, the only breeder of the Black Rock in the country, has maintained his high standards of breeding. The Black Rock is a consistantly good bird in all kinds of free range conditions. Over the past decades we have sold birds around Scotland and they have coped, nay thrived, in some of the most inhospitable places.
It is very unkind to put the commercial hybrids, with their weak feathering, poor immune systems, limited ranging, and high food value demands, outside in some of our exposed garden, croft and smallholding situations. Its a terrible thing to do to ex-battery birds, which have known only a completely protected environment for all their lives. Few gardens in most of the UK provide anything like the sort of environment they need. Unfortunately they are stoic, and put up with so much humans throw at them, in the name of providing us with food and then in salving some sort of anthropomorphic conscience about it.
In constrast the likes of most pure breeds and birds like the Black Rock have been given the qualities by our breeding over the generations to really be able to thrive in the vagaries of the outside world.
What is a Black Rock hen? - the Black Rock hen is an extremely attractive bird, predominantly black with variable amounts of chestnut colouring around the neck. She is very productive, laying up to 280 eggs a year in ideal conditions. In most domestic situations, which are rarely ideal in productivity terms, they are still generous enough to give over 230 or more eggs a year. In ideal conditions this can be as much as 280 eggs a year.
She is bred from very special and uniquely selected strains of Rhode Island Red and Barred Plymouth Rock from a single hatchery in the East of Scotland. This is the ONLY source of Black Rock birds. All the grand-parent and parent stock are bred by the same person - Mr Peter Siddons. Fortunately there are people around the country who, like us, take youngsters, from day old chicks upwards, and grow them on to pullets ready for you to take on, so that the birds are available to you for your situation. There is a link to acknowledged growers, like us, around the country here.
Obviously we can only supply birds to people who can come and collect them from the farm here. We free range rear all our birds and are limited in the numbers we can raise each year by the weather and amount of housing we have. Frequently we are booked up well in advance of the birds going away.
I have seen pics of birds just like mine on BYC, but I don;t know what you call them there. My girls are lovely.Nice brown eggs and a good size.
Hope this helps,
Jena.