1. For those participants where the oesophagus will receive a high dose of radiation due to it lying close to the cancer, the first part of the trial will establish the maximum safe dose of radiotherapy to the oesophagus. The first group of participants will receive a slightly higher dose than is currently used to treat lung cancer. If these participants do not have any significant side effects, a second group of participants will receive a slightly higher dose than the first group. This process will continue incrementally until side effects from the treatment become evident, thus demonstrating the maximum dose that can safely be given. Once the maximum safe dose to the oesophagus is known this will be classed as the recommended Phase II dose and all further patients entering the trial will receive no more than this dose to the oesophagus.