One of the chief interests in researching your ancestors is finding out what they did for a living. But many occupations have changed over the years, and so has the vocabulary. So what exactly was a Sagger Bottom Knocker? a Throstle Doffer? Here, in no particular order, are some useful free glossaries and other resources that may help to find out what your English ancestors were up to.
Pottery Jobs Index
An A-Z of jobs in the Potteries, this is part of thepotteries.org, an excellent local history resource for Stoke-on-Trent. Many entries have links to an entire page of information and illustrations. (This is where you will find the Sagger Bottom Knocker, hanging out with the Blunger Operator and the Bank Odd Man.)
Mining Occupations
Provided by the Durham Mining Museum, this is an authoritative glossary extracted from four 19th-century sources, largely (but not entirely) relating to the Durham and Northumberland coalfields. Detailed explanations are provided for some occupations. Sadly, the list includes many references to children, such as the wailer (the boy who picked out the impurities from the coal) and the foal, a small child who assisted a slightly bigger youth (headsman or putter) in dragging coal from the workings to the larger passages. If the foal and the headsman were of equal strength they were known as half-marrows.
Obscure Old English Census Occupations
A general alphabetical index of terms found in UK census returns, some of which are obvious but others that are less so. Rather oddly, part of a stock photography website.

Victorian Occupations (1891)
An alphabetical listing of occupations found in the 1891 census of London. Again, a mixture of the obvious and the obsolete, including some one or two startling anachronisms (Armiger, ‘Squire who carried the armour of a knight’). But one mustn’t be a Quarrel Picker (glazier: one who fitted quarrels, the small panes of glass used in lattice windows).
Occupational Codes
A bit later in date than most of the lists, but still highly useful, this is a digital edition of the Dictionary of Occupational Terms Based on the Classification of Occupations used in the Census of Population, 1921, originally compiled by the Ministry of Labour. Arranged within categories, but also including a dictionary of occupations, it covers nearly 30,000 terms, a good many of them now obsolete, such as the disturbing decomposing pan man who ‘charges shallow iron pans with salt and sulphuric acid…’ in the paint-making (etc) industry.
Kindly provided by Peter Christian (2016).
Cotton Industry Jobs
A list of selected occupations in the Lancashire cotton mills, compiled by Andy Alston from family knowledge and ancestry research. Includes some illustrations.
The Book of English Trades and Library of the Useful Arts: with Seventy Engravings (1818)
Slightly less convenient to use than the modern glossaries, this is available through Hathitrust, Google Books and elsewhere. It provides a detailed contemporary account of many early 19th-century trades, with some atmospheric engravings. Some comments may jar upon the modern ear (The journeyman’s earnings are good; but we fear, as in numerous other trades, that his habits are not calculated to induce him to make the most of them). The level of detail is fascinating: who knew, for example, that in the hat-making trade:
… beer-grounds are applied in the inside of the crown, to prevent the glue from coming through to the face, and also to give the requisite firmness at a less expence than could be produced by the glue alone …. In France, however, they use wine…
and finally….
The Oxford English Dictionary
The magnificent OED has to have the last word as the definer of the obsolete and the obscure. However, many occupational terms were just too obscure or localised to find their way in. Accessible free if you are lucky enough to have a local library or other institution that subscribes to this essential reference work.