The typical asking rate per listing is in the $0's per square foot per year. The London submarket is experiencing a decline in rates. In the last 3 months, the median rate fell $40 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 0 listings have been listed, which means office spaces most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About NaN% of the available space in the London are subleases, so you will probably have to focus your search on direct office leases. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around sqft. Most properties in this region are around 2 floors. Most buildings in this region were built in 1959 and are Class C.