Thanks to the lashing rain, and an early detour caused by the fact that I'd forgotten my pyjamas, we arrived slightly late for our dinner reservation at this coastal outpost of the much-loved Two Fat Ladies seafood restaurant group, newly opened in the grand old Marine Hotel in Troon.

However, our delay was a blessing in disguise, for we'd just missed a car bursting into flames outside the hotel, and the mayhem that ensued meant we would have been barred from entering until the vehicle was towed away.

Such dramatic beginnings augured a memorable visit, whose twin highlights had nothing to do with the watersports, wedding parties or golf outings that the ancient South Ayrshire seaside town has become famous for. The food and the spa proved more than adequate compensation for having to forgo our planned morning hike along the beach to ogle the kite-surfers we'd heard about, because the weather was so atrocious.

In the end we did manage to brave the beach for a few minutes, as it seemed shameful not to experience the bracing beauty of its wide sandy vista, restored dunes, and great views out to Arran. (It's worth noting that Troon's is one of the few west coast beaches to have been granted the Clean Beach Award.)

Catering on a grand scale is all very well, but the rambling Victorian red-brick Marine Hotel - now part of the Puma Hotels Collection - is leading something of a culinary shake-down in the town with the creation of its new signature restaurant, an intimate space that focuses on locally caught seafood, with decor that includes an eye-catching panel of Vivienne Westwood-designed wallpaper featuring fantastical fish. It's a bold move, given the enduring reputation of MacCallum's of Troon's dockside oyster bar just yards away.

In the restaurant, all tables have a view over to Arran from front-facing windows. We wondered about the decorative pewter birds placed at each table, and were informed by the front of house manager - who has come here from Restaurant Martin Wishart in Edinburgh - that they originated at The Buttery in Glasgow, where Two Fat Ladies has its flagship restaurant.

There are no amuse-bouches or appetisers here; you go straight to the starters. This is just as well, for my special of seabream fillet atop a butterbean, tomato and chorizo stew was not only blow-away delicious; it was also quite filling. The robustness of the butterbeans, enjoying a bit of a moment in the culinary spotlight, was a match for the smoky flavour of the spicy sausage and together they complemented the distinctive firmness of the fish, which was delivered to the table sizzling and with a properly crispy skin. It was a knockout start to our meal, and signalled that the kitchen had embarked on a new direction.

My companion's mussel and chorizo risotto with a - hello! - smoked tomato oil was an added hint that chef had his vision firmly fixed on exciting horizons.

I wouldn't have guessed that the crumbly black pudding in the centre of my main of pan-fried scallops was from Stornoway, as it wasn't immediately recognisable as such; chef had added to it his own ingredient of diced apple, a show of culinary flair that transformed its appearance and provided enough acidity to cut through the pudding. A smoked haddock cream with samphire countered this with its salty, creamy depth to provide the most delicious balance of flavour and texture.

The freshest piece of flash-fried halibut, simply seasoned with a well-judged sprinkling of sea salt, accompanied by a stunning deep-flavoured orange langoustine bisque and sitting on a bed of Parmesan mash so beguiled us that we almost - I did say almost - felt we could dispense with dessert.

After some feigned hesitation we tried a crême brulée (they clearly have no truck here with the trendy habit of renaming this French classic "burnt cream") with stewed plums and an orange and polenta shortbread. The cream was rich and cool with a pleasant sugary crackle; the plums, served separately on the plate in chunks and a little puddle of jus, pink and properly tart; the shortbread put my friend, a skilled shortbread baker, into blissful orbit. My raspberry poached pear also took my breath away; standing upright on the plate, stalk on, it glowed like a bejewelled lightbulb throwing its light onto an elliptical quenelle of creamy Glayva cranachan and a disc of honey toasted oatmeal. The seasonal fruit yielded firmly under my fork, and it tasted simply divine: the two fruity flavours a very cool blend indeed.

And so, next morning, to the spa, where two local girls made our visit comfortable despite the fact that we arrived at 9am while the place was hardly warmed up (our early appointment was designed to allow us to fit in breakfast before service closed at 10am).

My friend opted for a Decleor facial, and I chose a full body massage. I was initially disappointed that the oil had no fragrance; I feared I would be neither refreshed nor becalmed, but in the end the neutrality of the experience did help free the spirit.

Which seems an apt metaphor for the waves being created by Troon's newest arrival.

Two Fat Ladies at the Marine Hotel, Troon, Ayrshire KA10 6HE 01292 676220  www.twofatladies restaurant.com