This paper presents experts’ opinions on benefits of PBT and the level of provision for PBT utilization in the UK. The most reliable figure for percentage of radical radiotherapy patients likely to benefit from PBT was at 4.3%. The biggest estimated potential benefit was from reducing toxicity, median benefit to 15%, followed by dose escalation median 3%. Head and neck cancer is considered to benefit most from both reducing toxicity and dose escalation. Both CNS and lung cancer are also identified as potentially benefitting large numbers of patients, however clinical evidence is lacking.