The NHS is likely to face a High Court action soon about cancer patients’ right to top up their care with drugs paid for privately while they continue to receive the rest of their treatment free.

At least two patients have lodged claims that challenge the Department of Health’s guidance A Code of Conduct for Private Practice, issued in April 2003, which tells trusts not to permit patients to pay for additional drugs.

Dozens of patients have consulted lawyers, who hope to get a test case to court before the end of …