Act MP David Garrett may have been speaking for a sizeable number of people when he sought a guarantee that customary title would not be granted over some of the country's famous beaches after a new foreshore and seabed law is passed.

Unease has been generated by Attorney-General Chris Finlayson's statement that customary title is "an ownership title".

This creates a considerable breach with the existing 2004 legislation, which vested the foreshore and seabed in the Crown.

Iwi and hapu whose claims succeed will receive a deed giving title to a coastal area.

They will not be able to sell the property or block public access, but they will have considerable control, including the ability to veto or initiate development, permit activities, and exploit non-nationalised minerals.

The Prime Minister has been keen to offer assurances that any alarm is much overstated.

He says the compromise reached between the Government, the Maori Party and the Iwi Leadership Group means that, from the staging post of the public domain, there will be few awards of customary title by the courts or as a result of negotiation with the Crown.

That, says John Key, is because the threshold for the granting of such title is high.

Iwi and hapu applicants will have to show continuous and exclusive occupation of the area claimed since 1840.

There cannot have been any substantial interruption since that date, such as sale of the land, a port being built there, or use by the military during wartime.

Nor, the Government seems to believe, can thousands of people have been using the land for, say, recreation, with the local iwi not exercising any control over use or occupation.

It is on this point that it is possible to question Mr Key's confidence that few titles will be granted. It seems there will be no definition of exclusivity in the yet-to-be drafted legislation that replaces the Foreshore and Seabed Act.

Mr Finlayson says "exclusivity" is a common law concept "which requires the applicant group to demonstrate their interest in a particular area is generally akin to ownership in that they are able to exclude non-members of the customary title-holder group".

In effect, however, it seems that it will be left to the courts to define "exclusivity".

Here, the suggestion that iwi have ruled themselves out of customary title by allowing thousands to use a beach - rather than actively excluding them - will doubtless be challenged.

Some will surely argue that, while they had the ability to exclude, they chose not to exercise it and allowed use of the beach.

Much, therefore, will hinge on the exact wording of the legislation, and how much the Government, finally, decides to leave in the hands of the court.

Maori groups were keen to lower the threshold for customary title claims. What they had received in that regard was a removal of the requirement in the common law test for applicant groups to have continuous ownership of land next to the foreshore.

But the overarching exclusive possession test remained. What they gained in the final round of negotiations was an assurance that those coastal iwi who had already settled Treaty claims would still be able to apply for customary title, as well as a universal recognition of the mana tukuiho (legacy) of iwi and hapu to foreshore and seabed.

All parties claimed they were satisfied with the outcome. That, in itself, was considerable progress from a time when the Prime Minister was forced to appeal for "realism".

Indeed, there remains much to be admired about Mr Key's determination to find a cure for what he has termed a "weeping sore". But work still needs to be done. The devil will, indeed, lie in the detail of the new legislation that emerges in August.