Most family photographs arrive without a date. A studio mount may be blank, an album page may be torn, and family stories can be vague. The good news is that clothing, hairstyles and studio props can give you a surprisingly narrow window. Fashion moved quickly, especially for women and children, and photographers copied the latest styles. Use costume as a first clue, then confirm it with mount style, photographer's address, census records and family knowledge.

Start with the silhouette, not the fabric

Before you peer at buttons and stitching, step back. The overall shape of a sitter tells you more than any small detail. Women's fashion changed most obviously: shoulder line, sleeve shape, waist position and skirt length. Men's clothing changed more slowly, so a man's suit is often less useful for dating. Children's clothes are wonderfully helpful because they followed adult fashion closely but with shorter hemlines and simpler cuts.

Look at the neckline, collar, cuffs, waist, hem, hat and hair. Then study the studio itself: painted backdrop, carved chair, potted fern, patterned carpet, book, balustrade or rustic bench. These props date the photographer's working period as much as the sitter's clothes. A good rule of thumb: if a woman has a high collar, tight waist and long skirt, think 1880s to 1900s. If she has a short skirt and a bob, think 1920s. If she has padded shoulders and a turban, think 1940s.

The early decades: 1840s to 1860s

In the earliest photographs, women wore sloping shoulders, tight bodices and wide skirts supported by petticoats, then by the crinoline from the mid-1850s. Pagoda sleeves, wide at the cuff and narrow at the shoulder, appear in the 1850s. Hair was centre-parted, often with ringlets or a lace cap. Men wore frock coats, high collars, cravats and waistcoats. Children were dressed in petticoats and dresses until about five, then moved into short jackets and trousers.

Studio settings were simple: a plain backdrop, a table with a cloth, perhaps a book or a daguerreotype case. If you see a woman in a crinoline with a shawl, the photograph is likely from the 1850s or 1860s. If the image is a small, cased portrait, it may be earlier still.

Bustles, tailoring and leg-of-mutton: 1870s to 1890s

The 1870s brought the bustle back, with a cuirass bodice that fitted closely over the hips and a long corset. Hair was dressed high, often with curls. By the 1880s, silhouettes became narrower and more tailored, with jersey fabrics, high collars and hair pulled back tightly. The 1890s is the decade of the leg-of-mutton sleeve: very full at the shoulder, narrowing to the wrist, worn with bell-shaped skirts, shirtwaists and straw boaters.

Men in this period increasingly wore lounge suits and bowler hats, and moustaches were common. Children appeared in sailor suits or velvet Fauntleroy suits with lace collars. Studios offered painted scenes, ferns, balustrades and rustic benches. Watch for the sleeve: if it puffs dramatically at the shoulder, think 1890s.

Edwardian elegance and wartime change: 1900s to 1910s

The 1900s is the age of the S-bend corset, the pigeon breast, lace blouses, high collars, wide-brimmed hats and pompadour hair. By the 1910s, skirts narrowed into the hobble shape, then became looser and shorter during the First World War. Women's uniforms, munitions work and even trousers appear in family albums from this time. Men wore three-piece suits, wing collars, bowlers or fedoras. Children were still in sailor suits and pinafores.

Studio backdrops turned Art Nouveau, with rustic props and softer lighting. If a woman has a pigeon breast and a wide hat, likely 1900 to 1910. If she wears a simple uniform with short hair, likely 1916 to 1918.

The modern look: 1920s and 1930s

The 1920s brought a dropped waist, shorter hems, cloche hats, bobbed hair, silk stockings, long beads and tanned skin. Men wore plus fours, wide trousers, soft collars and fedoras. The 1930s favoured bias-cut dresses, longer hems, shoulder pads, waved hair and berets. Studios became streamlined, with close-up portraits and natural light. Watch the waist: if it drops to the hips, think 1920s. If it returns to the natural waist with padded shoulders, think 1930s.

Utility, New Look and the post-war decades: 1940s to 1950s

The 1940s meant utility clothing, padded shoulders, short skirts, turbans, victory rolls and uniforms. Men wore demob suits, wide lapels and trilbies. The 1950s brought the New Look: nipped waists, full skirts, petticoats, short hair, glasses and cardigans. Men's fashion included Teddy boy drape jackets and bomber jackets. Studio portraits often appear in colour and with more informal poses.

Use this checklist as you work through a box of photographs:

• Compare three things: silhouette, hair and accessories.
• Look at children first: their clothes date fastest.
• Check the mount: card thickness, corners and photographer's name.
• Cross-check: census returns, birth dates, military service and known family moves.
• Be cautious: people wore old clothes, especially in rural areas and among older sitters. A photograph may be later than the fashion suggests.

No single clue proves a date. But costume, hair and props together can turn a vague "Victorian" into a confident "about 1895". Enjoy the detective work, and record your reasoning alongside the photograph for the next generation.