Change ringing on practice nights and for services is usually performed in 5-10 minute bursts known as touches. These usually contain between 120 and 240 changes, rung to preordained sequences derived from one or more methods.
A quarter peal consists of between 1250 and 1440 changes and lasts for about 45 rung continuously and starting and ending in rounds. A peal is, as its name suggests, four times as long as a quarter and must contain at least 5000 changes.
On the bells at Vernet a full peal generally takes a little under three hours to ring. Anything more than about 6000 changes is known simply as a 'long length'. The record, set in 1963, by one band ringing continuously currently stands at 40320 changes, when the extent (all the possible changes) on eight bells was rung on the light ring at Loughborough Bellfoundry.
Ringers perform peals and quarter peals for various reasons, perhaps before a special Church service, in memory of a departed person or for notable feast days such as Christmas or Easter. For example, in the UK in 2012, such performances rang out to mark the Queen's Diamond Jubilee and the opening of both the Olympic and Paralympic games.
Details of all the peals rung at St George's can be found here, courtesy of the Ringing World's Bellboard.