The merger of Aldershot & District with Thames Valley took place on 1st January 1972, to form the new company known as Alder Valley. In preparation for this in late 1971 the liveries were changed to maroon with cream relief but this was short lived and the new standard National Bus Co livery of poppy red was adopted. The first buses to appear so were in December 1972. The two fleets of buses were renumbered into a common scheme and the routes were also renumbered, but later in September 1974 new vehicles were to the NBC standard of Leyland National and Bristol VR's although some smaller buses were needed and 35 Ford R1014's were bought in 1974 and 1976. All were withdrawn by 1980, some only 4 years old.
On 1st January 1986 the company was split into two, AV South and AV North to prepare for privatisation following a government Transport Act on 30th October 1985. This began the mini bus era in 1986 when 41 16 seat Ford Transits were delivered and a new mainly green livery was introduced for AV South. AV North was sold in January 1987 to Q Drive who operated it under the Bee Line name with a mainly yellow livery. In November 1987 AV South was sold to Frontsource LTD who continued to operate as Alder Valley, dropping the South from the fleetname, albeit for a short time, until they sold out in November 1988 to Q Drive under Mr. Len Wright's ownership. Thus the two halves of the company were reunited.
This was to be short lived due to problems within Q Drive as cash had to be raised quickly so some parts of the new company had to be sold off. In December 1990, Guildford, Woking and Cranleigh depots were sold to Drawlane LTD and placed under control of a new company, Randomquick LTD who operated as Alder Valley West Surrey. In December 1990 part of the Bee Line was sold to form the Wycombe Bus Co. and in 1992 the Reading and Newbury Depots transferred to the ownership of Reading Buses. On 26th October 1992 Alder Valley ceased to exist, having been sold to the Stagecoach Group and renamed Stagecoach Hants and Surrey.