What new cistern and flush pipe do ineed

Yes — you do not necessarily need a new pan. You can buy a cistern-only replacement, but the safe choice depends on how your existing pan connects to the flush pipe.

The key point is this:

If you want the least risky replacement, buy another high-level cistern and keep the same style/layout. High-level cisterns and flush-pipe kits are still sold, including kits where the pan and cistern are not included together, and retailers also sell cistern-only high-level options.
You may be able to change to a low-level cistern, but only if your existing pan is compatible with a low-level flush-pipe arrangement and the outlet/plumbing dimensions work. Toilet buying guides stress checking the existing plumbing and compatibility before changing the toilet configuration.

So, in practical terms:

Best option: replace like-for-like with a high-level cistern only.
That avoids guessing whether your pan will suit a low-level setup.

Only switch to low-level if:

your pan has the right flush-pipe entry position for it, and
you are happy to alter pipework/fixings if needed.
That is more of a measured conversion than a straightforward swap.

What to check before ordering:

inlet position on the cistern: side inlet or bottom inlet
flush-pipe diameter and connection style
mounting/fixing centres
whether you need cistern only or cistern + high-level flush pipe kit + brackets
whether your old “Dolphin” setup is plastic or ceramic, because that affects what will swap in neatly
My advice would be:

If your current toilet works fine apart from the cistern, order a high-level cistern only plus any flush-pipe/bracket parts you need, rather than trying to convert it to low-level. Victorian Plumbing also lists a high-level flush pipe kit separately, which is useful if the pipework or brackets are tired.

If you want, send a photo of:

the full toilet,
the cistern,
where the flush pipe enters the pan,
and the water inlet side,

and I’ll tell you which type to buy.

Yes — you can replace your old high?level Dolphin cistern without replacing the pan, but you need the right parts and fittings.

To replace a high-level Dolphin toilet cistern without buying a new pan, you need to purchase a cistern-only unit and, in most cases, a compatible flush pipe kit. High-level cisterns are still widely available as standalone

If you can share a photo of the area and existing an accurate idea on what will work.
To replace the High level cistern you’ll require cistern, downward flush pipe, new flush cone.
This all depends on compatibility with existing toilet pan.
A low level cistern in plastic or ceramic is also an option existing pan being compatible.
Victoria or better bathrooms I believe offer the high level cisterns only.

You don’t have to replace the toilet pan—just the cistern and flush pipe. For a like-for-like swap, look for a high-level or high-wall cistern kit
These are sold separately and usually include:
vitreous china or plastic cistern
chrome or copper flush pipe
pull chain and fittings
Measure the distance from the wall fixing brackets to the centre of the pan inlet so you can match the flush pipe length and diameter

???? Step 1: Assess the Existing Setup
• Cistern Type: Confirm that your current cistern is indeed a high-level model. These cisterns are typically mounted on the wall or ceiling, with a flush pipe connecting them to the toilet pan.
• Flush Pipe Dimensions: Measure the diameter of the flush pipe (commonly 2 inches or 50mm) and the distance from the cistern outlet to the pan inlet. This measurement is crucial for selecting a compatible cistern.
• Overflow Mechanism: Determine whether your cistern has an internal or external overflow. Modern cisterns often feature internal overflows, which might require adjustments to your existing setup.

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????? Step 2: Selecting a Replacement Cistern

You have two primary options:

1. High-Level Cistern Replacement
• Pros: Maintains the traditional aesthetic and functionality.
• Cons: May require adjustments to existing flush pipes and brackets.

2. Mid-Level Cistern Conversion
• Pros: Easier to install with modern flush mechanisms.
• Cons: Might necessitate repositioning the flush pipe and securing the cistern at a lower height.