Barberry. 

Berberis thunbergii f. Atropurpurea Nana - Barberry is a dense dwarf rounded deciduous shrub with reddish-purple leaves turning brilliant red in Autumn. Grows to about 40cm. Suitable for use as an edging plant.

Eventual height and spread up to 0.5 to 1 metre

This is a deciduous shrub so it will lose all its leaves in autumn shooting fresh new growth in the spring