One of the four Lost Marbles, as I call them; the songs from the proper double CD version of Marbles that weren't included on the streamlined, stripped down single CD version released out in the real world because "record shops generally don't like to sell double albums".
What's the worst thing you've ever done? Whatever your answer, whatever criteria you're defining it by, you know what it is, because, well... that sticks with you. It'll stay with you forever, no matter how you try to leave it at the bottom of a bottle, or focus on happier things. There will always be that voice that will remind you, in your darkest times, you are capable of this.
And so it is with the only unforgivable thing that Steve Hogarth has ever done, whatever that might be. It's left pretty open to interpretation throughout. And, uh, that's a lot of out to keep it through; "The Only Unforgivable Thing" opens and closes with some lovely church organ sounds, and the bit in between is pleasantly melancholy, but man does it go on a bit, without ever really changing much. It's not the worst offender for this on Marbles, but still probably the most deservedly absent of the four omissions they made in condensing the sprawling double album down to the one CD that was released to the unenlightened plebians who have not yet found a better way of life.
Other people have said this before me, but I'll repeat, because it is definitely true: There is a fantastic single album somewhere in Marbles, it's just not quite the one they actually released. This song, however, doesn't appear on the real or the ideal.