Dozens of homes had to be evacuated after an unexploded shell and gun parts were found in a removal container shipped in from South Africa.
Police were called to Copsey Removals in Crow Lane, Romford, on Tuesday, at about 4.15pm.
The container arrived on the site last week and staff said they became suspicious when they noticed that it had been packed by the owner, instead of one of their agents.
They then alerted HM Revenue and Customs.
Alby Tebbutt, the owner of Copsey, said: “I was in the garden at the time when I got the call saying that something suspicious had been found on the site.
“I wasn’t surprised. Most of the things that come on to the site are packed by our agent at the dock, so we knew something was wrong with this when it said ‘packed by owner’.”
HM Revenue and Customs officers arrived at the scene at about 3pm and started rummaging through the container.
They called bomb disposal experts when they discovered something resembling an explosive.
The Army experts advised that the site and houses nearby should be evacuated.
At 5.20pm the bomb was removed and staff and residents were told that it was safe to return.
Alby said: “There were lots of people just hanging around not knowing what was happening.
“It will probably cost us a lot of business because the staff were just outside waiting to be told when it was safe to come back.”
A range of items have been found in Copsey containers over the years.
Fifteen years ago, a hand grenade and guns were discovered in a container that had arrived from South Africa and £5million worth of heroin also turned up in a container eight years ago.
Alby said: “It is something that we have had to get use to.
“We have had to deal with them so many times, so we don’t panic.”