I was profoundly mortified at——

No one regrets more than I do the——

It was a matter of no small regret that——

It has not been very good fortune to——

Had I but served my God with half the zeal I served my king, he would not in mine age Have left me naked to mine enemies.

King Henry VIII., III., 2

Poignant regret

Frankly regretted

I feel like calling myself a simpleton for——

Unmistakable signs of a change of heart