Portsdown and Horndean Light Railway
Summary
Photographs of Portsdown and Horndean staff taken prior to the Great War are extremely scarce, but those that do exist indicate that staff wore double-breasted jackets, with two rows of four buttons and lapels, the style being very similar to that worn by their corporation counterparts during the first decade of that system's life (see link). The collars, cuffs and trousers were all piped in a lighter colour than the main body of the jacket. The left-hand collar bore system initials in individual metal letters, either 'P & H L R' or 'P H L R'. Caps were military in style with a glossy peak and tensioned crown (top); they bore script-lettering grade badges, either Motorman or Conductor. It is unclear whether the P&HLR used brass or nickel insignia.
Although lighter more modern materials were used in later years, the basic style of the jacket remained the same.
Double-breasted greatcoats were also issued, though it is currently unknown whether these bore any insignia. In later years, staff certainly wore large round municipal licences; these were very probably introduced in 1924 when through running over Portsmouth metals began; this was in marked contrast to corporation staff, who had not worn licences since the introduction of numbered cap badges in the Great War.
The 1903 photograph below shows an inspector wearing a single-breasted jacket with lapels, along with a matching waistcoat; both garments appear to have been corduroy, and were without badges of any kind. The cap was military in style with a tensioned crown and glossy peak, and bore a script-lettering grade badge Inspector, probably metal rather than embroidered. What style of uniforms were worn by inspectors in later years is yet to be determined.
The company presumably employed female staff during the Great War to replace men lost to the armed services, however, photographic evidence is lacking, so details of their uniforms remain unknown.
For a detailed history of the area's tramways, see 'Tramways of Portsmouth' by S E Harrison, Light Railway Transport League (1955).
Images
Motormen and conductors
A staff photo taken at Cowplains Depot in 1903. With the exception of an inspector, all those wearing uniforms are conductors, motormen presumably being amongst those present wearing informal attire. Photo with kind permission of Hampshire County Council (see link).
A blow-up of the above photo showing four of the youthful looking conductors; their right-hand collars bear system initials ending in 'R', so presumably either 'P & H L R' or P H L R'. Their caps carry standard, script-lettering grade badges.
Standard ‘off the shelf’ script-lettering cap badges of the type used by the Portsdown and Horndean Light Railway, though it is currently unclear whether they issued them in brass or nickel. Author's Collection.
Portsdown and Horndean Tramcar No 16 stands in St Helens Parade Portsmouth, along with Portsmouth Corporation Tramways Car No 44 — photo undated, but certainly taken no earlier than 1924 when through running of company cars over corporation-owned tracks commenced, and probably as late as 1930. Photo probably by Dr H Nicol, with thanks to the National Tramway Museum. 
A blow-up of the above photo showing the motorman, who is wearing a large round municipal licence, very possibly identical to those previously worn by corporation staff before their displacement by numbered cap badges in 1916. With thanks to the National Tramway Museum. 
Motorman at the controls of Tramcar No 17, an ex Gosport and Fareham Tramways car — photo undated, but certainly taken after the closure of the latter system (31st December 1929). Photo courtesy of the Tramways and Light Railway Society, with thanks to David Voice.
A conductor and motorman pose for the camera with a rather careworn Tramcar No 11 — photo undated, but probably taken very late in the tramway's life (i.e., the 1930s). Uniforms were clearly in short supply by this time, as the conductor is wearing casual trousers. Photo courtesy of the Tramways and Light Railway Society, with thanks to David Voice.
The crew of Tramcar No 16 at the Canoe Lake/Granda Rd terminus — photo undated, but probably taken in the early 1930s. Photo by H Nicol, courtesy of the National Tramway Museum. 
A blow-up of the above photo showing the conductor and motorman (the latter inside the car).
Senior staff
A blow-up of the 1903 staff photo above showing the inspector, in what would appear to be a corduroy jacket and waistcoat.
Script-lettering Inspector cap badge — brass. It is currently unclear whether the P&HLR issued its staff with nickel or brass badges.