Cigarettes are being sold in standardised green packaging bearing graphic warnings of the dangers of smoking from today, under new rules designed to prevent young people taking up the habit.
All packs must contain a minimum of 20 cigarettes to make sure the packs are big enough for health warnings to cover 65% of the front and back, with the brand name restricted to a standard size, font and colour.
The EU Tobacco Products Directive has allowed the UK to go further with its regulations to require all tobacco packaging to be uniformly green with large images showing the harmful effects of smoking.
Packaging of hand-rolled tobacco must also be in the same drab green colour and contain a minimum of 30g of tobacco.
Tobacco giants failed in a last ditch legal challenge against the Government's new plain packaging rules at the High Court on Thursday when a judge rejected a judicial review action brought against Health Secretary Jeremy Hunt by four of the world's biggest firms.
The companies now have a year to sell old stock and fully implement the changes under the directive, which was adopted in 2014 but has been held up by a series of court cases testing its legality.
It includes a ban on menthol cigarettes from 2020 and promotional statements such as "this product is free of additives" or "is less harmful than other brands".
The new rules are an attempt to cut the number of smokers across the EU by 2.4 million.
An estimated 700,000 premature deaths are caused each year, and cancer charities are backing the measures.
British Lung Foundation chief executive Dr Penny Woods said: "For too long glitzy, cleverly designed packaging has lured young people into smoking, a habit that takes the lives of half of all long-term smokers.
"Australia introduced plain packaging in 2012 and has already seen a decline in smoking rates. If just a fraction of the 200,000 children in the UK who start smoking a year are discouraged, thousands of lives will be saved."
But Simon Clark, director of the smokers' group Forest, said the new packaging rules "treat adults like children and teenagers like idiots".
He said: "Everyone knows the health risks of smoking and no-one starts because of the packaging.
"Australia was the first country to introduce standardised packaging and it hasn't worked. There is no evidence to suggest that smoking rates have fallen among children or adults as a result of the policy.
"Plain packaging is a declaration of war on consumers because the aim is to de-normalise not just the product but also the millions of adults who enjoy smoking and don't want to quit."
Blogging for the Huffington Post UK on Friday, Daniel Hunt, a policy advisor for Cancer Research said it was "utterly shameful" that the tobacco industry "spent so much time, effort and money trying to block measures that will help prevent cancers in the future".
Hunt added that the packaging changing are historic in the UK "and their impact cannot be overstated".
"Finally, we'll see cigarettes for what they really are - a vehicle for an early grave that is entirely avoidable.
"So out goes the glitzy, gift-wrapped cigarette pack, and in comes a gift to protect future generations from cancer.
"And today we can celebrate that."