The only other British species recorded in the Outer Hebrides that is superficially similar is the six-spot burnet. It flies at night but can often be disturbed during the day from long grass. The yellow and black striped larve are quite distinctive. Its main food plant is ragwort (Senecio jacobaea) but other related plants are also used. The flight period is May through to July.
The cinnabar is a comparatively recent arrival in the islands and appears to have just about established itself at the lower end of South Uist. There are odd records elsewhere each year but they seem to be just transient sightngs as they are not followed up in later years with subsequent records. To try to establish the current distribution Outer Hebrides Biological Recording have organised a survey of cinnabar and six-spot burnet moths. You can discover more about this and related projects on the OHBR website. The survey guide has some identification hints, as the two species both have a bold black and red colouration that, whilst making them easy to separate from most other moths, can be quite confusing if all you get is a brief glimpse.