A Study to Determine the Feasibility and Acceptability of Conducting a Phase III Randomised Controlled Trial Comparing Stereotactic Ablative Radiotherapy With Surgery in paTients With Peripheral Stage I nOn-small Cell Lung Cancer cOnsidered Higher Risk of Complications From Surgical Resection

Inclusion Criteria: 1. Primary tumour characteristics. 2. Peripherally located tumour as defined in the RTOG 0236 study and UK SABR Consortium guidelines. This states that the tumour must be more than 2cm in axial diameter from a major airway. * This includes the trachea, carina, right and left main bronchus and extends to the bifurcation of the right upper, right middle, right lower, left upper and left lower lobe bronchioles 3. No evidence of hilar or mediastinal lymph nodes involvement. * Any hilar or mediastinal lymph nodes that are either * PET positive or \>1cm in axial dimension must be sampled by mediastinoscopy, endobronchial ultrasound or oesophageal endoscopic ultrasound and demonstrate negative cytology and/or pathology 4. Local lung cancer MDT consensus opinion that patient is considered suitable for either surgical resection or SABR treatment AND also to be at higher risk complications from surgical resection 5. Age ≥ 18 6. Female patients must satisfy the investigator that they are not pregnant (negative pregnancy test within 72hrs of surgery of day 1 surgery/SABR), or are not of childbearing potential 7. Able and willing to provide written informed consent Exclusion Criteria: 1. Previous radiotherapy within the planned treatment volume. 2. History of clinically significant diffuse interstitial lung disease 3. Any history of concurrent or previous invasive malignancy that in the opinion of the investigator could impact on trial outcomes 4. Clinical or radiological evidence of metastatic spread 5. History of psychiatric or addictive disorder or other medical condition that, in the opinion of the investigator, would preclude the patient from meeting the trial requirements 6. Previous systemic therapies, including targeted and experimental treatments, for their current lung cancer diagnosis