To think this ?party guy? needs help?

[TeaRose]

One of my friends ? the office party animal ? asked me if I thought he has a problem with drinking. Knowing him socially from occasions where he was only mildly more plastered than the rest of our rather merry colleagues, I said no. He looked relieved ? then let slip he got so drunk he couldn?t remember the evening five nights a week.

And when I asked him how often he thought about having a drink, he said ?Not in the morning. Only after lunch?.

Should I, er, revise my decision and have a gentle word?

Yes.
He asked for your opinion, and obviously suspects himself that he is drinking too much.

I'd speak to him, telling him you've been thinking about what he said earlier, and that you didn't realise how much he drinks. If he cannot remember the night before it's time to sort his drinking out.
He came to you about this, and you hopefully will be able to help him sort himself out.

Since he asked you, yes you should be honest. He obviously asked you because he thought you would be straight with him, and probably not judgemental. So do tell him, and hopefully he'll be able to sort it.