Apple Pay makes its big debut in the United Kingdom today, and it does so with support from a long list of banks. However, many of those won't be available until later on — including HSBC, which was expected to be one of Apple Pay's launch partners in the U.K.

When Apple announced the arrival of its new payments service for the U.K., HSBC was one of several major banks and credit card companies that were to provide support on day one. But customers quickly discovered that they were unable to add HSBC cards when Apple Pay went live this morning.

Now, the Apple Pay support page on Apple's U.K. website lists HSBC as coming soon, and the company is telling customers on Twitter that it will be arriving "later in July."

Meanwhile, Barclays, another major British bank which originally chose not to support Apple Pay at all, has now reversed its decision. After a torrent of complaints from disgruntled customers, the company announced on Twitter that it will add support for the service "in the future."

U.K. banks that are offering Apple Pay support today include American Express, MBNA, Nationwide, NatWest, Royal Bank of Scotland, Santander, and Ulster Bank. Those adding support "soon" are Bank of Scotland, First Direct, Halifax, HSBC, Lloyds Bank, M&S Bank, and TSB.

Apple Pay is supported at more than 250,000 retail locations across the U.K., including stores like Boots, Marks & Spencers, Lidl, Waitrose, and of course, the Apple Store. It's also available inside a whole host of iOS apps.