In 1989, licencing legislation passed by Margaret Thatcher's Conservative government made it possible for a Tied pub to stock at least one Guest Beer from a different brewery. The Right Honourable Margaret Hilda Thatcher, Baroness Thatcher, LG, OM, PC, FRS (born 13 October 1925), is a British politician. ... In the UK a tied house is a public house that is owned and operated by a brewery. ... An amusingly named pub (the Old New Inn) at Bourton-on-the-Water, in the Cotswold Hills of South West England A pub in the Haymarket area of Edinburgh, Scotland A public house, usually known as a pub, is a drinking establishment found mainly in the United Kingdom, Ireland, Canada...

The Monopolies and Mergers Commission was concerned that the market concentration of the big six brewers at 75% represented a monopoly situation. The Supply of Beer (Tied Estate) order of 1989 allowed publicans freedom buy non-beer drinks from any source (not just the controlling brewery) and to sell at least one draught beer from a different brewery. The entrance of a brewery. ... In economics, a monopoly (from the Greek monos, one + polein, to sell) is defined as a persistent market situation where there is only one provider of a kind of product or service. ...

In addition to this, many of the larger brewers were forced to sell many of their breweries off, with the intention that they would become free houses or pass on to smaller brewers, hence increasing choice and free trade. The unintended consequence of this legislation was that the brewers sold off their less profitable pubs. A free house is a British pub that is owned independently of the brewery (or breweries) that supply it. ...