Complex sentence: The odds of Ireland's win at the contest varied between bookmakers, ranging from 25-1 up to 51-1, However, the writer of the song John Waters believed that Dervish could win the contest.
Split into simpler sentences: The odds of Ireland's win at the contest varied between bookmakers, ranging from 25-1 up to 51-1. However the songwriter of the song John Waters believed that Dervish could win the contest.