Portsmouth Street Tramways
(including the Landport and Southsea Tramways Company, the General Tramways Company of Portsmouth, the Gosport Street Tramways Company and the Portsmouth [Borough] Tramways Company)
Summary
The Portsmouth Street Tramways Company was a subsidiary of the Provincial Tramways Company, and though it operated its first horsecar service in 1874, it actually grew to become the sole Portsmouth horse tram operator following its amalgamation with its close neighbours — the Landport and Southsea Tramways Company (opened in 1865), the General Tramways Company of Portsmouth (opened in 1878) and the Gosport Street Tramways Company (opened in 1882). All four companies were owned by the Provincial Tramways Company, but were operated as one entity — the Portsmouth Street Tramways Company - from 1883 onwards. The company also operated the Portsmouth (Borough) Tramways services from 1886, taking over that company completely in 1892.
Photographs of the three companies with which the PSTCo was amalgamated have not survived, so it is not possible to say what attire its employees wore. A few good quality photographs of the PSTCo do however exist, including one from 1881, so it is possible to give a reasonable description of what was worn from then until the municipal take-over (1st January 1901).
Drivers wore smart but informal attire, most often consisting of a shirt, tie and heavy duty greatcoat or coachman's coat, along with the horse driver's favourite headgear of the period, the bowler hat, though in later years the straw boater also made an appearance (in summer presumably). Conductors also wore informal attire: shirt and tie, jacket and single-breasted greatcoat, but with a squat kepi-style cap; the latter seems to have borne a small cap badge, which may simply have been an employee number, as photos are suggestive of a difference in size (i.e., one digit versus two). The company not only required conductors to wear these caps, but apparently expected them to buy them too!
It would be all too easy to conclude that the conductors' greatcoats were issued by the company, given the general similarity in styles, however, the fact that caps were self-purchased, would tend to suggest that greatcoats were too, and that any similarity was due to a tendency to purchase them from the same supplier.
Drivers and conductors also wore a large round municipal licence, attached to either the coat or in the conductor's case, his cash-bag strap.
Between 1896 and 1901, the PSTCo also operated an experimental petrol/kerosene-fulled steam tram — manufactured by the Liquid Fuel Engineering Company (LIFU) — where the engine and passenger accommodation were combined into a single vehicle, supplemented with a trailer. Few photographs have survived, but those that have suggest that the crews wore jacket, shirt and tie, along with a soft-topped cap, all without badges, and almost certainly self-purchased rather than issued by the company.
Photographs of inspectors have not come to light, and it may well be that the tramway never employed them.
For a detailed history of the area's tramways, see 'Tramways of Portsmouth' by S E Harrison, Light Railway Transport League (1955).
Images
Horse tram drivers and conductors
A conductor and driver pose with an unidentified horsecar on a service from The Hard to Lake Road — photo purportedly taken in 1881. Photo courtesy of the Tramways and Light Railway Society, with thanks to David Voice.
A blow-up of the above photo which reveals the driver to be wearing a bowler hat with a curved brim (characteristic of the 1880s), whilst the conductor has a squat kepi-style cap bearing a small cap badge. The driver is also wearing a round licence.
An unidentified and somewhat battered PSTCo tramcar and crew — photo undated, but probably taken in the 1890s. Author's Collection.
A blow-up of the above photo showing the crew, the conductor in kepi-style cap and informal jacket, the driver in long coachman's coat with a bowler hat; both men are wearing licences.
The conductor and driver of Horsecar No 68 captured for posterity — photo undated, but definitely taken after 1894 as No 68 was only built in that year. Photo courtesy of the Tramways and Light Railway Society, with thanks to David Voice.
A blow-up of the above photo showing the conductor and driver; whilst the former sports a bowler hat, the latter has a squat kepi-style cap bearing a small badge. Both men are wearing large round municipal licences. 
Conductor and driver pose with an unidentified horsecar — photo undated, but definitely no earlier than 1890 when this car was built. Photo courtesy of the Tramways and Light Railway Society, with particular to David Voice.
A blow-up of the above photo. Once again the driver is wearing a bowler hat and the conductor a squat kepi-style cap bearing a small cap badge.
Steam tram drivers and conductors
A well-known shot of the LIFU steam tram operating on the Landport and Southsea route — photo undated, but almost certainly taken shortly after delivery in 1896. Photo courtesy of the National Tramway Museum. 
A blow-up of the above photo showing the driver and conductor (possibly). Both men appear to be wearing informal attire, almost certainly self-purchased, with soft-topped caps, the entire ensemble devoid of badges or licences.