Greaves' Rules is a set of etiquette guidelines common in the UK for buying rounds of drinks in English public houses. The rules were first defined by William Greaves, a now (2011) retired London journalist of the defunct Today newspaper as a Saturday morning essay in the paper, based upon his long experience of pubs and rounds.  They immediately attracted a wide following in drinking circles and are known internationally as a representation of the spirit of drinking in an English pub.
When an individual arrives at a pub, common practice invites the newcomer to unilaterally offer a drink to a companion, with the unspoken understanding that when the drink has been nearly consumed, his/her companion will reciprocate. Trust and fair play are the root of the rules, though there are occasions (such as a requirement of one of the drinkers to need to carry out more important jobs, if any can be conceived of) where the rules can be broken, and were itemised by Greaves in his article. See, for example a copy of Greaves' Rules in the Oxford Pub Guide, with particular reference to rule 7 and especially rule 8.
Greaves' Rules is a lighthearted set of rules governing whose turn it is to buy a round of drinks in a British public house. The rules were first published as a Saturday essay in the now defunct Today newspaper but were later re-commissioned by the Daily Telegraph and published in that newspaper on 20 November 1993. Copies of the rules soon appeared in many bars throughout the UK and are now known internationally as a representation of the spirit of drinking in a British pub.
1. When two or more enter the pub together, one - usually the first through the door - will begin proceedings with the words "Now then, what are we having?" He or she will then order and pay. This purchase is known as "the first round".
2. This player, or "opener", will remain "in the chair" while other friends or colleagues come through the door to join the round. He will remain in this benefactory role until either (a) his own glass sinks to beneath the half way mark or (b) another drinker finds himself almost bereft of his original refreshment and volunteers to "start a new round".
3. In the absence of new arrivals, any player other than the opener may at any time inquire whether it is "the same again?" On receiving his instructions, he will then order and pay for "the second round". (N.B. The second round is the last one to be specifically numbered. Beyond that point, nobody wishes to be reminded how many they have had and, anyway, no-one should be counting.)
4. The round acknowledges no discrimination. All players, regardless of sex, age or social status, are expected to "stand their corner". (Pedants might like to note that we are talking here of the only "round" in the English language that also contains a "corner".
5. Any new entrant, joining the session after its inception, is not expected to "buy himself in" but should be invited to join the round by whoever is in the chair (see Rule 2). If, however, he is greeted by silence he may either (a) buy a drink just for himself or (b) attempt to buy a round for all present. If (a) or, worse still, (b) is not acceptable to the congregation then the new entrant has been snubbed and should in future seek out more appreciative company. There is one important exception...
6. For reasons of haste or poverty, a new arrival may insist on buying his own with the words "Thanks, but I'm only popping in for one". If he is then seen to buy more than three drinks, he will be deemed a skinflint, neither broke nor in a hurry to get home, and will be penalised for his duplicity by being ordered to buy the next round.
7. Although everyone in the group is normally required to buy at least one round before leaving, the advent of either drunkenness or closing time sometimes renders this ideal unattainable. In such circumstances, any non-paying participant will (a) have "got away with it" and (b) appoint himself "opener" at the next forgathering. However, any player who notices on arrival that the round has "got out of hand" and has no chance of reaching his turn before "the last bell", may start a "breakaway round" by buying a drink for himself and all subsequent arrivals. This stratagem breaks the round in two, keeps the cost within manageable proportions and is the only acceptable alternative to Rule 5.
8. When a pressing engagement elsewhere precludes further involvement, it is wholly unacceptable for any player who has not yet been in the chair to buy a round in which he cannot himself be included. In such circumstances Rule 7 (a) and (b) therefore apply.
9. In the event of any one glass becoming empty, a new round must be called immediately. This should not necessarily be called by the owner of the empty glass, however, because this place the slower drinker at an unfair fund-saving advantage. (N.B. Whereas it is permissible for any member of the round to decrease the capacity of his individual order - "just a half for me, please" - the opposite does not hold good. A large whisky, for instance, may be offered by the chair but never demanded of it.)
10. Regional variations. In various parts of the country, a particular establishment will impose its own individual codicil. In one Yorkshire pub, for example, the landlord's Jack Russell terrier expects to be included in every round. Where such amendments exist, and are properly advertised, they must be piously observed. We are, after all, talking about a religion. 
Kate Fox, a social anthropologist came up with a similar idea in her book Watching the English, but concluded their rationale was the need to minimise the possibility of violence between drinking companions.
- Gutfeld, Greg. Lessons from the Land of Pork Scratchings, London: Simon and Schuster, 2008. ISBN 978-1-84737-066-2
- William Greaves (3 September 2010). "Pub Talk". Gentlemen Ranters (162). Retrieved 15 May 2011.
- "Pub Etiquette". Sunriseag.net. Retrieved 2011-05-22.
- "Предприятия питания в Великобритании". www.ducland.ru. Retrieved 2011-05-22.
- "Pub Etiquette". Sunriseag.net. Retrieved 2011-05-22.
- "Watching the English - The hidden rules of English behaviour". Sirc.org. 2004-04-22. Retrieved 2011-05-22.