UPDATE 2-England's 'freedom day' marred by soaring cases and isolation chaos

* England lifts most COVID restrictions

* Johnson forced to isolate after trying to skip it

* PM urges caution as cases rocket to 50,000 a day

* Businesses say app causing isolation chaos

* Clubbers dance through dawn
(Adds shares and sterling)

By William James

LONDON, July 19 (Reuters) - Prime Minister Boris Johnson's
'freedom day' ending over a year of COVID-19 lockdown
restrictions in England was marred on Monday by surging
infections, warnings of supermarket shortages and his own forced
self-isolation.

Johnson's bet that he can get one of Europe's largest
economies firing again because so many people are now vaccinated
marks a new chapter in the global response to the coronavirus.

If the vaccines prove effective in reducing severe illness
and deaths even while infections reach record levels, Johnson's
decision could offer a path out of the worst public health
crisis in decades. If not, more lockdowns could loom.

But Johnson's big day was marred by "pingdemic chaos" as a
National Health Service app ordered hundreds of thousands of
people to self-isolate - prompting warnings supermarket shelves
could soon be emptied.

"If we don’t do it now we’ve got to ask ourselves, when will
we ever do it?" Johnson said just hours after he was forced to
abandon a plan to dodge the 10-day quarantine requirement for
himself and finance minister Rishi Sunak.

"This is the right moment but we’ve got to do it cautiously.
We’ve got to remember that this virus is sadly still out there."

Britain has the seventh highest death toll in the world,
128,708, and is forecast to soon have more new infections each
day than it did at the height of a second wave of the virus
earlier this year. On Sunday there were 48,161 new cases.

But, outstripping European peers, 87% of Britain's adult
population has had one vaccination dose, and more than 68% have
had the two doses which provide fuller protection. Daily deaths,
currently at around 40 per day, are just a fraction of a peak of
above 1,800 seen in January.

The FTSE 100 share index fell to a two-month low on Monday
on concerns that economic recovery could be in danger. UK-listed
shares of cruise operator Carnival Plc, and airlines
easyJet and British Airways-owner IAG fell
between 4% and 6.7%. The pound fell to a three-month low.

'FREEDOM DAY'?

From midnight, laws in England requiring masks to be worn in
shops and other indoor settings lapsed, along with capacity
limits in bars and restaurants, and rules limiting the number of
people who can socialise together.

Johnson sets COVID-19 restrictions for England, with
devolved administrations in Scotland, Wales and Northern Ireland
making their own policy.

As businesses across England faced a shortage of workers due
to the NHS app pinging people and telling them to isolate,
supermarkets warned they faced strain.

"It’s a major issue across every industry at the moment,"
Marks & Spencer CEO Steve Rowe said. "Our COVID cases are
roughly doubling every week and the pinging level is about three
to one of COVID cases, so we’re seeing that growing
exponentially."

"If there’s shortages we’ll have to manage it by changing
hours of stores, reducing hours. Where the industry will see the
pain is in the supply chain, because logistics runs tight anyway
to be efficient."

British society appears split on the restrictions: some want
tough rules to continue as they fear the virus will keep killing
people and overwhelm hospitals, but others have chafed at the
most onerous restrictions in peacetime history.

Johnson faced an outcry on Sunday when he and finance
minister Sunak tried to dodge quarantine with a special scheme
for senior ministers and civil servants. He will now isolate at
his country residence at Chequers after health minister Sajid
Javid tested positive.

As the dawn rose over London, clubbers danced through the
night at one of the first rule-free live music events since the
pandemic began last year.

"I have not been allowed to dance for like what seems like
forever," said Georgia Pike, 31, at the Oval Space in Hackney,
east London. "I want to dance, I want to hear live music, I want
the vibe of being at a gig, of being around other people."
(Writing by William James and Guy Faulconbridge
Editing by Frances Kerry and Giles Elgood)