Stevenage is roughly 30 miles (50 km) north of central London. Its population has increased significantly over the last century: the population was 1,430 in 1801, 4,049 in 1901, 79,724 in 2001 and 84,651 in 2007. The largest increase occurred in the 1950s and 1960s, after Stevenage was designated a new town under the New Towns Act of 1946.
For more information, see the EN Wikipedia article Stevenage. There is a long history section.