Among horse-drawn vehicles, a trolley was a goods vehicle with a platform body with four small wheels of equal size, mounted underneath it, the front two on a turntable undercarriage. The wheels were rather larger and the deck proportionately higher than those of a lorry

Lorry (horse-drawn)

Among horse-drawn vehicles, a lorry was a low-loading trolley. It was used mainly for the carriage of other vehicles, for example for delivery from the coachbuilders or returning there for repair....

. A large trolley is likely to have had a headboard with the driver's seat on it, as on a lorry but a smaller trolley may have had a box at the front of the deck or the driver seated on a corner of the deck and his feet on a shaft. With a very small trolley, the 'driver' may even have led the horse as a pedestrian. They were normally drawn by a single pony

Pony

A pony is a small horse . Depending on context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. There are many different breeds...

 or horse

Horse

The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

 but a large trolley would have a pair.

It was primarily an urban vehicle so that, on the paved roads, the small wheels were not a handicap. In any case, the axles would normally be sprung. It was typically used by market fruiterers and greengrocer

Greengrocer

A greengrocer or fruiterer is a retail trader in fruit and vegetables; that is, in green groceries. Greengrocer is primarily a British and Australian term, and greengrocers' shops were once common in suburbs, towns and villages...

s but commonly also by coal merchants. These would have a headboard to stabilize the front row of sacks which then held up the next and so on. The deck was at a good height for taking the bags onto the coalman's back and there was no protruding rear wheel to obstruct his access to them.

Many ended up with rag and bone

Rag and Bone

"Rag and Bone" is a song by the American garage rock band The White Stripes, and is the ninth track on their album Icky Thump. The track was released as a free red 7" vinyl with the June 6, 2007 issue of the NME magazine, with 120,000 copies made and an etching with drummer Meg White's face on...

 merchants who were likely to add side and tail boards to keep their purchases aboard.

The largest and sturdiest trolleys were those used with lift vans

Trolley and lift van

The trolley was a platform body with four relatively small wheels mounted underneath it, the front two on a turntable undercarriage. It was drawn by a pair of horses and the driver's seat was mounted on the headboard....

.

As in many fields, as time went by, people used the word without understanding its detailed meaning so that it became applied less precisely and other configurations were given the name and some trolleys were known by other names. For example, the electric milk float

Milk float

A milk float is a battery electric vehicle , specifically designed for the delivery of fresh milk. They were once common in many European countries, particularly the United Kingdom, and were operated by local dairies...

 is more a trolley than a float

Float (horse-drawn)

A float is a form of two-wheeled horse-drawn cart with a dropped axle to give an especially low loadbed.They were intended for carrying heavy or unstable items such as milk churns. The name survives today in that of the milkfloat....

, as is the brewer's 'dray' seen at horse shows.