The harps I have listed as 'baroque Welsh' (only Evans at present) date from the later 17th century on, and are still made and played in a living tradition today. They use the Italian system and not the Spanish systemm, and always have three ranks of strings; the two outer ones tuned as unisons, and level with each other, and the centre rank placed alternately with the outer ranks and tuned to the chromatic notes.
Welsh baroque harps have a different shape from both Spanish and Italian harps; the soundbox is much shorter, and so the neck rises much higher to give similar bass string lengths. The soundbox is more strongly tapered, and so deeper and wider in the bass, than Italian harps; more like Spanish ones.
It seems that baroque Welsh harps were usually made and played the opposite way round from Italian and Spanish and German baroque harps, using a left orientation. It's interesting to note that the left orientation of the baroque Welsh harps led their makers to insert the tuning pins from the left side of the neck, and the strngs on the right. All other European harps, both Continental instruments used with a right orientation and Irish harps used with a left orientation, have the pins inserted from the right and the strings on the left of the neck. In this context it is worth noting that James Talbot in the later 17th century remarks that diatonic Welsh harps are strung normally, that is with the pins inserted from the right so the strings fall on the left, in contrast to the chromatic triple harps. I do not know of any extant diatonic early Welsh harps.
In the early 19th century there was a deliberate revival of Welsh baroque harps, by this time at least known as Welsh Triple harps. The tradition almost died out in the late 19th century, but one person continued to play in the old style using left orientation on an antique triple harp, Nansi Richards. Her students including Llio Rhyderch are still performing today.