With the wall-to-wall festivals now upon us, it has to be smoked salmon season. The luxury treat is a given for celebrations - how else would you end your Yom Kippur fast if not with a slice of challah topped with smoked salmon and a steaming cup of tea?

According to Lance Forman, owner of H Forman & Son, although smoked salmon is now a ubiquitous product, quality is on a downwards spiral.

"Most mass-market produced salmon is awful. People assume if they don't like it that it is an acquired taste, but they haven't tried the real thing. I spend most of my time educating people about how properly smoked salmon should taste," he says from his office opposite the London 2012 Olympic Stadium. The building - which also houses Forman's restaurant - is salmon pink and has a curved fishy form.

Recalling a tasting with three top chefs for consumer body, Which?, he says: "At the pre-tasting, each of them said none of the salmon was smoky enough; however, it's not about the smoke, but about preserving the taste of the salmon.

"Much of smoked salmon is now mass produced to a price, which has devalued it. What you can easily end up with is a slimy texture and an overpowering taste of smoke."

Forman explains that as part of the traditional smoking process, salmon is salted, drawing 10 per cent of the water from it. Less moisture equals less weight. Bad news if you're selling it by the kilo. So, many manufacturers now inject the fish with a salt solution instead.

Fish should be as fresh as possible prior to smoking. But Forman says there is a cost implication of using only the freshest fish, as it inevitably takes time to get here from where it is caught. Two thirds of salmon used for smoking is sourced from Norway, which can take four days to arrive, so the fish is already ageing. A heavier smoke successfully disguises this. This smoked salmon will either taste very smoky or even acrid.

"Of the salmon sold at Billingsgate, 95 – 99 per cent is Norwegian. Even some Scottish smoked salmon producers buy their fish from Norway to smoke in Scotland."

Another trick he says the industry uses to prolong shelf life is to add sugar.

"It's hydrophilic, which means it causes the fish to retain water (and weight) and it also helps preserve the fish. Sugar also disguises bitterness from the smoke. You should never see sugar in ingredients for smoked fish - it's not an ingredient that was used historically."

Forman says his company - started by his great grandfather who began smoking fish in London in 1905 - always uses Scottish salmon and never uses fish more than two days old.

"We use the exact same processes my great grandfather followed when he came here from Odessa in the late 19th century. We hand fillet our fish - a mixture of wild and farmed. You can't use a machine when the fish is so fresh it still has rigor mortis."

The Formans were not the only Jewish immigrants who made their living smoking fish.

"It was a predominantly East London trade and until the 1970s there were a number of smoke houses in the East End. Then grants were given for salmon farming in Scotland and smoke houses popped up all over the country. The London smoke houses couldn't compete."

Forman explains that his family did not even try to compete on price but continued to smoke using their traditional methods.

"They would not compromise but what has happened now is that we have become part of the artisan foodie movement. Ironically, by not modernising, we have survived."

Formans are not the only artisan producers of smoked salmon. Several smokeries have popped up - some of which are Norwegian-owned.

And Formans has managed to secure government approval for its London Cure, the first protected geographical indication status (PGI) from the EU for a London food manufacturer. This status protects Forman's London Cure smoked salmon from imitations and recognises it as a premium product.

"We're just waiting for the rubber stamping to close the process," says Forman.