The fire is now out at the factory in Greenwich which burst into flames in the early hours of the morning.
The area still smells strongly of the swimming pool chemicals which were stored here.
The fire brigade say those chemicals pose little health risk to anyone and are no worse than a strong bleach.
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John Cantlie, who worked for a number of Fleet Street newspapers, is thought to have been taken hostage in November 2012.
The union published a 'no show' league table for last year the worst offenders for cancellations.
Zalkalns was jailed in his native Latvia for eight years in 1988 after he admitted killing his wife with a piece of electrical equipment.