Niall:
Where, exactly, on The Old Course did you wish you could use your 7-iron instead of your putter while on the green? I am just trying to get a sense of what you're talking about.
To whomever it was who asked earlier:
The greens at Old Macdonald are all "big", but there is also a variety of big, bigger and giant. I would guess the smallest ones are around 7000 sf, with the largest pushing 20,000 sf. The hardest green to hit in regulation would almost certainly be #10 -- it's possibly the smallest green, it's sharply elevated at the front, and you play it in a tailwind. Or perhaps the Redan, downwind. Really on both of those greens it is scary to even TRY to hit them; if trying to post a low score, I'd be happy laying up to the front in both cases.