On average, listings lease in the $10's per square foot per year. The Brent region is seeing a a boost in rates. In the last 3 months, the median rate went up $0 per sqft per year. That's a 2% rise in rent.
In the last 90 days, 11 listings have been made available, which means new listings most likley are going fast. You'll want to be prepared to make an offer immediately. About 145% of the available leases in the Brent are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,790 sqft. Most buildings in this market are approximately 1 stories. Most buildings in this area were built in 1979 and are Class B.