What I'm looking for in this batch of links is a set of people in clothing that indicates a sort of uniform of affinity – while just about any clothing could be livery, the garments in these links are indicative of a group of people dressed similarly because the clothing was given to them as livery.

There's a better way to word that. This linkspage is still in development, and may be for a while. There's a lot more to the concept of “livery” than I've addressed. It’s often a form of salary paid to one’s household retainers & servants, etc. These garments do not say “I am this person” (as a personal heraldic surcoat) or “I speak for this person” (as a herald’s tabard) but rather “I belong to (or in some cases, support) this person (or this geographic area, this political faction, this group, etc.).”

See also Livery Clothing circa 1460-1480 and 15th Century Livery Coats for Soliders.

NON-MILITARY CONTEXTS (civilian garments, servant & household livery, etc.)

• See description in pp. xxxvi-xxxviii of A roll of the household expenses of Richard de Swinfield, Bishop of Hereford
• Servants in the Knighting of St. Martin from the Scenes from the Life of St. Martin (Cappella di San Martino, Lower Church of San Francesco, Assisi) by Simone Martini, 1312-1317
• Dancing men in the Luttrell Psalter (British Library MS. ADD. 42130), c. 1320-1340
• Serving-boys at the Round Table (BNF Fr. 343, fol. 3), c. 1380-1385
• Angels wear gowns with the white hart badge of Richard II on the right panel of the Wilton Diptych, c. 1395-1399
• Servers and trumpeters at a banquet at the home of Charles V the Wise, Les grandes chroniques de France (BNF Fr. 6465, fol. 444v), c. 1455-1460
• Abraham’s retainers at The Meeting of Abraham and Melchizedek by Dieric Bouts the Elder, 1464-1467
• Servers at a meal at which Alexander (in disguise) dines with Darius III, Chroniques d’Alexandre (BNF Fr. 9342, fol. 105v), mid-15th century
• Servers at a dinner, Histoire de Renaud de Montauban (BNF Arsenal 5072 Res.)
• Trumpeters at a wedding-feast, Histoire de Renaud de Montauban (BNF Arsenal 5073, fol. 148), 1468-1470
• A joust, the Wolfegg Housebook (fols. 21v-22r), c. 1475-1485
• A page attending a nobleman visiting a merchant of precious stones, Mandeville Lapidary (BNF Fr. 9136, fol. 344), fourth quarter of the 15th century
• Detail from the Autumn section of the Augsburger Monatsbilder, 1520s
• Archers on fols. 11v and 12r of the Hennessy Book of Hours, c. 1530-1540
• Musicians at a ball in Augsburg, c. 1590-1595

MILITARY CONTEXTS (livery jackets worn over armor, battle scenes, etc.)

• The battle of Morgarten in the Tschachtlanchronik, 1470
• Swiss soldiers in the Berner Schilling chronicle, 1480s
• English soldiers wearing the cross of St. George as Richard I does homage to Philip for Normandy, Chroniques de France ou de Saint Denis (British Library Royal 20 E.III, fol. 155v), 1487
• Crusaders besiege Damascus (fol. 280v) and Siege of Jerusalem by Saladin (fol. 438), Chronique d’Ernoul et de Bernard le Trésorier (British Library Royal 15 E. I, fol. 438), late 15th century
• English soldiers guarding Charles, Duke of Orleans, at the Tower of London (British Library ROyal 16 F. II, fol. 73), c. 1500
• The Battle of Hard, aftermath of the Battle of Triboltingen, the battle of Bruderholz, the standoff at Novara, the battle of Ochsenfeld, mercenaries raid a village, battling over cattle in the Hegau, the battle of Sempach, attack on Marienfeld, in the Luzerner Schilling chronicle, 1513