Thanks FBBird and Devilfish - According to the illustration and description in Helm, the Purple-tailed Imperial has orange/ochre coloured feathers covering the whole head but the red orbital ring certainly fits the description. If it wasn't for the red orbital ring, I'd say it was more likely to be a Rufescent Imperial. Looking closely at the photo, there does seem to be a 'metallic reddish-purple' look to the upper tail coverts and a 'broad ashy-grey apical band' - both characteristics of the Purple-tailed.
