The station grew rapidly as traffic increased. Its workload increased from handling 2,700 parcels a month in 1838 to 52,000 a month in 1841. By 1845, 140 people were working there and trains began to run late because of a lack of capacity. The following year, two new platforms (later 9 and 10) were constructed on vacant land to the west of the station that had been reserved for Great Western Railway services. The L&BR amalgamated with the Manchester & Birmingham Railway and the Grand Junction Railway in 1846 to form the LNWR, with the company headquarters at Euston. This required a new block of offices to be built between the Arch and the platforms.