The incident came at the UK coffee shop chain’s Llansamlet outlet and customer Janine Hughes has hit out at what she regards as the company’s inadequate response to her complaint.

Tomorrow she is due to get the result of blood tests.

Miss Hughes, from SA1 in Swansea, went to the outlet with her partner and her father and ordered two lattes, one of which had blood on the lid. She said the employee who served her had a cut hand and went to wash it while another staff member changed the lid.

“He should have changed the coffee,” she said. “My partner had that coffee. I drove off and took two sips of mine, and it tasted irony, I realised something was wrong, but did not know what at the time. Then I saw blood on the inside of the lid and realised there was blood in the coffee. My partner had not tried his as it was very hot, and he didn’t then.

“I drove back and asked to see the manager. The person who served me was mortified. I felt sorry for him. He should have gone off to wash his hands and we should have had two new coffees. I was offered new drinks and was given two lattes but I said I had to report it. It was too serious to ignore.”

“The area manager was horrified and said something should have been done,” said the 30-year-old IT worker. “She was very apologetic.”

And she added: “I will ensure that my entire team will revisit all necessary training as an absolute minimum.”

 A head office statement said: “Our area manager has spoken to Ms Hughes and apologised for the distress this obviously caused her. This was an isolated incident and does not reflect our high standards of safety and hygiene.”

Miss Hughes said: “I don’t think it should have been the area manager to apologise. It should have been head office. Not once have they contacted me. They have hidden behind the brand. That is terrible.

Chris Peregrine /chris.peregrine@swwmedia.co.uk/@Perers71