IT has to be said that Jamie's Italian - Jamie Oliver's restaurant chain - isn't orthodox Italian.

Jamie does his own thing, so Italian in his book is pretty much an opportunity to throw together Italian ingredients in any way he sees fit. Squeeze a few lemons, rattle a few pans, reach for a jar of olives, and bish, bash, bosh, you're sorted.

But although Oliver takes licence with the recipes of il bel paese, he's a bit of a pedant when it comes to ingredients. No malarkey here. Having eaten in Jamie's Italian in Edinburgh, I am inclined to believe the guarantee that "we only use fresh, carefully sourced and seasonal ingredients to make all our beautiful, rustic dishes". The shopping list here is pukka, as Oliver would say, and I was pleasantly surprised to find that the cooking was actually rather good too.

That is some achievement as there are now heading for 40 Jamie's Italians in the UK, a scale that begets quality control issues. Recently I had a poorly cooked, badly served, overpriced meal in Raymond Blanc's Brasserie Blanc in Cheltenham, and there are only 20 of those. Even Michelin-starred Blanc can't keep on top of his extended restaurant empire, or so it seems.

Nowadays, there is Jamie everything - books, pans, crockery, cookery academies, even ships. He has gone into partnership with Royal Caribbean Cruises, who are putting Jamie's Italian restaurants into their new cruise ships, Quantum Of The Seas and Anthem Of The Seas. When he is not being an international businessman, he finds time for unpaid campaigning. His latest useful intervention is to speak out against the proposed TTIP (Transatlantic Trade and Industry Partnership), in my view, a sinister vehicle for corporations to force down European food quality and safety standards, privatise the NHS, and more. And the man has four young children. Heavens, does Jamie Oliver never sleep?

In decor terms, the Jamie's Italian in Edinburgh, housed in the former supper halls of the Assembly Rooms on George Street, with its ornate ceilings, elaborate cornicing, garnet walls, velvet chairs and spectacular chandeliers, must be one of the jewels in the chain's crown. We ate in the less glam, but almost more interesting area at the back, which gives you more of a cooking feel and a direct view into the kitchen. It is also possibly a few decibels quieter than the main area, but do be warned, the din here fairly builds up. This is an exceptionally noisy restaurant.

Crisp wafer-like "music bread" (Sardinian pane carasau) made a substantial "nibble", topped with thin wedges of Sardo pecorino, a chilli jam "mostarda" (more like an Asian sweet chilli sauce, if you ask me), curls of fresh chilli and mint leaves. It was proper pecorino, so the whole thing worked. We weren't bowled over by the porcini arancini because they didn't taste of porcini, and although they oozed melting Fontina (always an Alpine pleasure), the rice was a bit over-cooked. Crab bruschetta made up for that, the brown meat spread on toast, topped with the white, and dressed with diaphanous fennel, and lemon. You could really taste the Chianti and fennel in the ragù of slow-cooked fennel and free-range pork sausages. It was meant to come with pappardelle, and turned up with frillier tripoline instead, but this was a highly satisfactory dish. In much posher restaurants I would be delighted to be served Jamie's immaculately pink calves' liver and bacon, which came with a distinctly Sicilian fruity onion, raisin and pine kernel gravy; and I'd expect to pay more for it than £12.95. It would have gone really well with the bright green and white kale and cabbage slaw had several whole slices of un-separated pungent onion rings not overpowered it.

A chocolate Arctic roll was okay, if relatively prosaic and unmemorable. Sour cherry and almond tart looked heavy, but was dreamily moist, with a welcome amaretti biscuit flavour, and the sharp Amarena cherries really made their presence felt. It slipped down a treat with airy cream, whipped with honey.

Maybe I got lucky, but for a chain, Jamie's Italian isn't at all bad.