The lambs are reared on four farms on the central North Island west coast, two at Turakina, one each at Tangimoana and near Hawera. Being warm and coastal they lamb earlier than inland farms, from mid-June to mid-July.
Between them the farms can supply 2000 lambs a week, each aged only 90 to 100 days and fed on lush spring pasture.
The animals are killed by Land Meat at Wanganui, and the meat is available from November to the end of January.
Mr Redmayne began the venture to provide the best of spring lamb in New Zealand rather than having it shipped to the northern hemisphere for Christmas.
This year he's been working with the Australian head chef at Wanganui's Red Lion Inn, Sam Jones.
"As a local farmer it's extremely exciting to work with someone like Sam and offer our product to Wanganui and the wider province," he said.
Mr Jones said Tasmanian and King Island lamb was known as the best in Australia. "This is just as good, if not better."
Mr Redmayne and his wife Suze will be away most weekends to host tastings at supermarkets and food events, including the enormous Taste of Auckland. Stock manager Simon Perry was in charge of their 1005ha Tunnel Hill farm while they were away.
The Coastal Spring Lamb brand was developed by an Auckland company. Foodstuffs, owner of New World supermarkets, developed its sales material. Wanganui's Inferno Design & Advertising has made it a website where customers can learn about the farms and their families, restaurants, retailers and recipes.
The Wanganui District Council has been supportive, and its economic development manager Allan MacGibbon said the district needed more enterprises that added value to farm products.
This year's demand is unlikely to outstrip the 30,000 lambs the four farms will have available. Mr Redmayne said next year the brand could expand into the South Island, and even overseas.