Heavier vegetation can be quickly and effectively cleared without the need for burning. The flail cutting head will reduce a considerable quantity of growth to a scattering of wood chips. This has proved to be a safe reliable method of removing overgrowth from areas where access is poor and men working with chain saws would be dangerous.
If you have such areas that require clearing, you may be able to claim subsidies through DEFRA to help manage areas that are susceptible to invasive plants. See http://www.defra.gov.uk for more details.