The fire demolished industrial units in the estate which has forced businesses to down tools and look for new offices, one business owner has said.
Server Consultancy boss, Sanjay Mittal, said the IT business he has owned for 13 years has been given a notice to leave.
The Stanmore resident added his team of six people are currently working from home with a view to finding short-term space, but said it could take around six months to find a new permanent base.
Around £55,000 worth of equipment - including servers and furniture - was lost in the fire, which will be covered by insurance.
Mr Mittal added: "We have been told the building has been declared condemned, we're not going to get back to the building.
"This is the update from the estate. They said that the building is condemned, and as a result of the dangers a notice has been issued.
"We are looking for new offices, and we have spoken to insurance. They have assured us a temporary place at another office.
"You can't do anything about it, it is not easy to digest.
"When the news breaks, you don't really know the scale of the damage.
"You sit down and do the math and you realise it will take months to get back.
"We're using personal computers and phones. We might move in next week but getting a permanent office may take six months.
"We have got to prepare the building properly, with the servers, we have to make sure we are safe."
Getwestlondon has approached the owners of East Lane Business Park for comment.
London Fire Brigade (LFB) said the fire had been brought under control by 2.19pm on Tuesday (January 24), but that crews are still on the scene damping it down.
The cause of the fire is under investigation.
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