In centuries past, each parish in England would have had its own incumbent (the vicar or rector in charge of the parish), but more recently reductions in church attendance and income have forced many parishes to merge under a single incumbent to form a multi-parish benefice. In 1960 17% of parishes in England were part of a multi-parish benefice, whereas (as of 2019) it is 62%. (One source claims the number was 71% in 2011, but I don't know how they got that number. My figures won't include parishes in which the church has been closed completely, but they don't count as part of any benefice so can't affect that number.) Many rural areas have benefices with over a dozen parishes and churches, and each year more are amalgamated to form larger benefices usually under a single priest, perhaps with a curate (newly-ordained training priest) or occasionally other clergy.
Using the data from achurchnearyou (as of 2019), use the links below to find the total number of benefices, parishes and (Anglican) churches in a given diocese/archdeaconry/deanery/benefice, but also the benefices with the most churches.
To use the site, click on a diocese to list the archdeaconries into which it is divided. Archdeaconries are in turn divided into deaneries, which consist of benefices, which consist of parishes. Many parishes now have more than one Anglican church. (There are a couple of instances of single parishes in London with two benefices, but otherwise it's a strict hierarchy.) On any page the second table lists the benefices with the most churches for the restrictions you've selected so far and selecting a benefice will list the parishes within that benefice.
The Church of England's 'Diocese in Europe' is included for completeness, but its benefices are unusual in that they can span multiple European countries and of course have no 'parish', so can be ignored for the purposes of looking at multi-parish benefices.
|Bath & Wells||3||19||178||462||558|
|Sodor and Man||1||4||14||15||39|
|Southwell & Nottingham||2||9||144||238||295|
|St.Edmundsbury & Ipswich||3||18||116||442||477|
|Retford Area Team Ministry||28|
|North West Europe||27|
|South Cotswold Team Ministry||22|
|Italy and Malta||21|
|Launditch and The Upper Nar||19|
|The Winchcombe Team Ministry||16|
|Nadder Valley (Team Ministry)||16|
|Vale of Pewsey||16|
|Cheriton Fitzpaine, Woolfardisworthy, Kennerleigh,||15|