John Key's achievement on Saturday is historically remarkable. Only two post-war Prime Ministers, Sir Sidney Holland in 1951 and David Lange in 1987, have increased their party's share of the vote while in power. Mr Key matched their achievement at the 2011 election. This time he has increased National's share for a third time. That has not happened since 1925 when Sir Gordon Coates led the Reform Government to victory after the death of William Massey.
To find a precedent for the same leader increasing his party's seats at three successive elections we have to go all the way back to Richard Seddon in 1899.
That is the scale of the achievement. It is one that allows National to contemplate not just another three years in office but quite possibly a fourth term. That, however, depends on what happens now. The Prime Minister has made it clear he wants to continue with the partnerships he formed six years ago, though pending the count of special votes National might be able to govern alone.
With Act - whose failure to win party votes consigns it to remaining a National appendage - National is assured of enough seats to do what it likes. The first thing it might want to do with that power is to amend the Resource Management Act so that economic considerations can be given equal weight with the environment. The Maori Party and Peter Dunne were able to prevent this in the previous Parliament. Now National will not need their votes.
But if Mr Key maintains his previous character, he will not legislate in a subject as important as this without seeking broader support than he strictly needs.