Quick answer: A Hackney Carriage is licensed to "ply for hire" — it can wait at a taxi rank and be hailed in the street — while a Private Hire Vehicle can only take pre-booked fares through a licensed operator. Because Hackney Carriages operate more visibly, they generally face more prominent plate and signage requirements, and only a Hackney Carriage can display an illuminated roof sign. The exact rules for plates, door signs and roof signs are set by your local council, so always check your authority's current specification before you order.
If you're new to the trade, or thinking about switching between Hackney Carriage and Private Hire, one of the first things you'll notice is that the rules aren't the same. And that includes what you're required to display on your vehicle.
It's one of those things that seems straightforward until you're standing in front of a licensing officer trying to explain why your door sign doesn't match the spec. So here's a clear breakdown of what the two licences actually are, how they differ, and what that means for your plates, signage, and vehicle setup.
The basic difference between Hackney Carriage and Private Hire
A Hackney Carriage (what most people call a black cab, even though they come in all shapes and sizes now) is licensed to ply for hire. That means you can wait at a taxi rank, be hailed in the street, and take bookings. You operate more visibly, which is partly why the signage requirements tend to be more prominent.
A Private Hire Vehicle can only take pre-booked fares through a licensed operator. You can't pull up to a rank or be flagged down. The licensing is separate, the operator is brought into the equation, and the rules around what you display on your vehicle can be quite different.
Both require a licence from your local authority. Both require a licensed driver. But beyond that, the specifics vary (sometimes significantly) from one council to the next. For more on why the UK system works the way it does, see our guide on why UK taxi licensing is so different from other countries.
What this means for your vehicle
This is where it gets practical. The signage and plate requirements for Hackney Carriages and Private Hire Vehicles aren't always the same, and your local authority sets the rules for both.
External plates
Most councils require a rear-mounted licence plate showing your licence number and other details. The size, position, and design will be set by your council. Hackney Carriages often have more prominent plate requirements, sometimes front and rear. Private Hire plates can be slightly different in design, and in some areas the plates themselves are colour-coded to make enforcement easier.
MOGO supplies a full range of no-drill plate brackets and fixings to mount your plates securely without damaging your vehicle.
Door signs
This is where things vary most. Some councils require door signs on both sides of the vehicle. Some require them only on Private Hire vehicles. Some specify the size, position, and exact content. Others give more flexibility. If you're moving between council areas (or your operator covers more than one) this is worth double-checking before you order anything. MOGO produces custom taxi door signs made to your council's exact specification.
Internal windscreen licence
Both vehicle types typically need a licence displayed inside the vehicle, visible through the windscreen. Again, the format your council uses will determine what you need to display and how. A windscreen licence pouch keeps it visible and legible.
Roof signs
Hackney Carriages in many areas are required to have a roof sign — the illuminated kind that shows the vehicle is available. Private Hire vehicles generally can't use them, because displaying a roof sign when you're not licensed as a Hackney Carriage can land you in serious trouble with enforcement. MOGO supplies illuminated and non-illuminated taxi roof signs for Hackney Carriage use.
What happens when your licence renews
Councils do update their requirements. It doesn't happen constantly, but it does happen — a rebrand, a design change, a new specification for plate size or door sign content. When it does, drivers are expected to comply, and not everyone gets a clear heads-up that something has changed.
The most common scenario is a council updating their plate design or colour scheme. If your authority has moved to a new layout since your last renewal, the plates you had last year may no longer be compliant, even if they're still in perfectly good condition. The same can apply to door signs if the required content or format has changed.
So before you reorder anything at renewal, it's worth a quick check. Look at your council's current licensing guidance, or contact their licensing team directly and ask whether the specification has changed since your last issue. It takes five minutes and can save you from displaying something that's out of date.
What to do if you're not sure
Start with your licensing authority's handbook or guidance document — most councils publish this online. If the answer isn't obvious, call the licensing team directly. It's a much better conversation to have before you've ordered anything.
If you're switching between Hackney Carriage and Private Hire (or picking up a new licence for the first time), it's also worth checking whether your existing plates and signage will still be compliant, or whether you'll need to update them. Our guide to taxi signage compliance covers what every driver needs to know.
Frequently asked questions
What is the main difference between a Hackney Carriage and a Private Hire Vehicle?
A Hackney Carriage can ply for hire — it can wait at a rank and be hailed in the street — while a Private Hire Vehicle can only take pre-booked fares arranged through a licensed operator.
Can a Private Hire Vehicle display a roof sign?
Generally no. Illuminated taxi roof signs are reserved for Hackney Carriages. A Private Hire Vehicle displaying one can face enforcement action, because it implies the vehicle can be hailed when it legally can't.
Do I need taxi door signs on both sides of the vehicle?
It depends on your local council. Some require door signs on both sides, some only on Private Hire vehicles, and some specify exact size, position and wording. Always check your authority's current spec before ordering.
Are taxi licence plates the same in every council area?
No. Each local authority sets its own plate design, size and colour, and these can change at renewal. Plates that were compliant last year may not be after a council updates its layout.