The Journal of the English Folk Dance and Song Society, 9, pp. 1-41, 1960, contains an article by E. C. Cawte, Alex Helm, R. J. Marriot and N. Peacock, "A Geographical Index of the Ceremonial Dance in Great Britain". Ceremonial dances are there classified. There are few such dances from Wales or Cornwall (see fold out map between pages 39 and 40, and the index). The Abbots Bromley Horn Dance (Staffordshire) is the only known ceremonial, 1620-1956, where the participants used horns. There is a possibilty horns were used in a long defunct dance at Seighford in the same county. This is in Anglo-Saxon England, not Celtic England. So this can hardly be tied in any way to the Celtic god Cerunnos (His name is found only on an altar in Paris)

Nora Chadwick, in her book 'The Celts' points out the bull is a symbol of strength and virility, but says nothing about fertility).

The verse quoted above for "Hal an Tow" about wearing horns (also in the version in DT) is obviously about cuckolding, not about a horned god.

I fail to see anything in song, dance, or folk play relating to any horned god.