Here is a "time order" list of openings and events in MSA history. Please note that dates may not be correct, but are based on infomation gathered or supplied. Some sites are also missing from this list where I don't have an opening date for them, so don't use this as a master site index for the site! 
Looking at the list it is easy to see sudden spurts in development (such as 1972), and quiet periods ( such as 1977-82 and 83-86)

Take-A-Break enters MSA business

Granada Enters MSA business

Frankley M5

Esso enters MSA business with Taverna brand

Washington Birtley A1(M)

Michaelwood M5

Harthill M8

Birch M62

Esso (Taverna) leaves MSA business, sells sites to Granada (more)

Hamilton M74

Bothwell M74

Rownhams M27

Exeter M5

Government Prior Report changes MSA structure. Now to be a 50 year lease, as opposed to annual rent based on turnover (more)

Kinross M90

Ferrybridge M62/A1

Stirling M9/M80

Forte purchases Welcome Break from Hanson Trust

Tamworth M42

Government deregulates provision of MSA's- now can be 15 miles apart where there is a demonstrated need

Granda deal with Burger king to put franchised outlets in MSA's.

Cherwell Valley M40

Take-a-Break (who owned Stensham) had a management buyout from its owners (inchscape)

Welcome Break negotiate a long term turnover related lease with MacDonalds, who ran the MacDonalds stores with the MSA. This was different to Granada's earlier tie up with Burger King, which was a franchise.

Forte sites (Welcome Break) Aquired by Granada

Pavillion sites sold to Granada

Blue Boar had a management buyout from its owners for 325m

First purchases 2 services from Granada (management buyout)

Granada Sells off 21 Welcome Break 21 sites to Investicorp after Monopolies commision report. (more)

Welcome Break starts selling KFC

Oxford M40

Chester M56

Roadchef Acquired by Nikko Europe Plc for 175 Million pounds.

Roadchef Aquires Take-A-Break

Roadchef Aquires Blue Boar

Hopwood Park M42

Bridgwater M5

Granada Merges with Compass changes name of MSA's to Moto

Winchester M3

Cardiff Gate M4

Blackburn Interchange M65

Compass (moto) sells off Little Chef and Travelodge chain (more)

Telford M54

Several MSA companies close to collapse with poor share price.

Part of Welcome Break (its finance arm) went into recievership (more)

Plans announced for the new service area on the M20 (Folkstone)

Lord Forte Dies aged 98. (BBC news)

Nikko sells RoadChef to Israel property firm Delek for £375 million.

Plans for a new service area at Beconsfield on the M40 are made public

Thanks: "Jam Sandwich"