Treatment: One patient will be treated at one time with a single dose of CTX cells. Three ascending doses (20, 50 or 80 million cells), allocated sequentially, will be tested in 9-18 patients (3 dose cohorts of 3-6 patients. All trial patients will receive 10 intramuscular injections of CTX DP into the gastrocnemius muscle of their ischaemic leg on a single occasion. In the event that both legs have peripheral arterial disease, the injections will be administered to the leg determined by the Investigator to have the more advanced/severe disease provided that leg has not already had surgical amputation of toes or above.