She's been living with a debilitating medical condition for some time, and it's now forced her to rethink her career after eight years fronting the Hertfordshire prog outfit.

Seviour says in a statement: "As many of you will know, I've dealt with ME for the last five years. The condition and lifestyle changes that it has resulted in - including a move cross-country - have made it impossible for me to commit to Touchstone in the way that it truly deserves.