Tenantry Down is let to Sussex Wildlife Trust. The commons have a high conservation value with rare species, wetland, grassland and woodland habitats; they have an SSSI designation. At Ditchling Beacon you can see pockets of flower rich chalk grassland with many common orchids. However, the Beacon has two rarities of note – the musk orchid and marsh fragrant orchid. The musk orchid, only found in the south of England, can be hard to spot, growing just 7.5cm tall with a limey green colour. It is best looked for in July, where it may be seen on tightly grazed patches, often rabbit grazed land. Despite its name, this orchid is more honey-scented and does not smell of musk.
The marsh fragrant orchid on the other hand is a much blowsier more colourful plant, dark pink in colour. It can be found on the northerly scarp slopes of the Beacon where moisture holds in the ground for longer. Related to the fragrant orchid, it can grow to 70 cm tall and is best seen late June to August.
Lists of Commoners, their land and their grazing rights exist dating back to 1794. Their rights were attached to the land they were farming rather than to the Common itself. The total area of land to which the rights were attached was divided into 61 units, called yards, each yardholder having the right to graze either one horse or two bullocks on Ditchling Common and four sheep on Tenantry Down, such rights being known as “leazes”. The public too have rights over the Common.
The registration of the Commons under the Law of Property Act 1925, giving rights of “air and exercise” to the public, recognised in law what had been taken for granted for centuries. The right to “air and exercise” anywhere on the Common now officially applies to both pedestrians and horse-riders. The Commoners of today are the current owners of the parcels of land whose grazing rights were registered under the 1965 Act.