Health technologies being assessed: The trial will compare the outcomes of patients receiving Routine care plus Intermittent Pneumatic Compression (IPC) vs. Routine care and avoiding IPC. Patients allocated to IPC will be fitted with thigh length IPC sleeves although if these are not well tolerated, for instance because of heavy soiling due to faecal incontinence, below knee sleeves can be substituted. Ideally IPC will be worn both day and night for 30 days from randomisation OR until a second screening doppler ultrasound (if after 30 days). Routine care is likely to include general measures to reduce risk of DVT including, adequate hydration, routine use of aspirin in patients with ischaemic stroke and early mobilisation. It may also include routine use of graduated compression stockings (GCS) if these are shown to be effective in the ongoing CLOTS Trials 1 & 2. Participating centres will be asked to ensure that the standard care specific to their institution is applied equally rigorously to patients in the trial irrespective of their treatment allocation. Collaborators will be permitted to use these interventions where they feel this is clinically justified − we will monitor use of antithrombotics and GCS to ensure it is balanced in the two treatment arms.