It is ironic that the palace asked for the series to be held back until well after Elizabeth R, the BBC's portrait of the Queen, which was screened last February. Nobody could have anticipated the scandals of the summer, prompting accusations that the Royal Family has more money than is sensible and keeps too much of it. The programmes will do little to allay those charges, because although most of the Queen's gardens are open to the public, the priceless pictures are primarily for private delight.
The most surprising aspect of the two parallel series - and a symptom of the new shape of the television industry - is that both have been produced by the same independent company. Long gone are the days when the BBC would make such prestige programmes itself: now they are part of the 25 per cent of all production that it is required by the Government to farm out to independents.
Antelope Films, created 12 years ago by Peter Montagnon, formerly with the BBC, is one of the most successful independent production companies. Mick Csaky, its managing director, explains how he had unwittingly become producer-in-chief to the Queen's household - if not quite by royal appointment, at least by royal approval.
'Both ideas came from outside,' he says. 'Harry Marshall, a young independent, came to us in 1990 with the idea for The Royal Collection. We went together to see Christopher Lloyd. I insisted we must have access to the pictures in the private areas where they were hung. After several months of delicate negotiation, the Queen blessed the project.
'Then I went to Channel 4 and pitched it to Waldemar Januszczak, the commissioning editor for arts. He and Michael Grade saw it as a means of bringing a wider audience to masterpiece paintings through the intimacy of the Royal Family.
'Not long after that, the BBC approached me about Royal Gardens. Roy Strong had put it up to them through Antelope some years ago but they hadn't picked it up then. We had to do the same thing about negotiating access to the gardens, but before long that was up and running, too.'
Antelope took on a co-producer for The Royal Collection: the Japanese national broadcaster NHK. It is being shot on Japanese high definition equipment (HDTV) so that it can be shown in Japan on the few HDTV sets so far made. This has increased the cost of the series to pounds 800,000, but the Japanese are paying the extra costs.
'Before long we had the 16mm garden series for the BBC running on half the budget in the adjoining room,' Mr Csaky recalls. 'I decided to keep both productions apart. I think the teams crossed once in the car park at Hampton Court. We couldn't have used any common shots even if we had wanted to, because of the different systems used for filming.'
Royal television, though superficially glamorous, is not always good for the reputation of its makers because of the impression that they have to kowtow to the palace to get access.
'I don't think there's any danger of Antelope being typecast as a court producer,' says Mr Csaky. 'One of our major recent series was The Midas Touch, about greed and money in the late Eighties, and before that we did one about drugs in a Thai monastery.
'This time we did have to pay greater than usual attention to protocol, but we were still able to perform well. In neither case did the Royal Family make any promise to appear. I think at the beginning we were very much on a watching brief.
'Subject to our performance en route, more collaboration and generosity were extended towards us. To our delight, towards the end of the garden project, Prince Charles offered to show us around Highgrove.'
The Queen appears in both series. In Royal Gardens she is seen walking the corgis in the grounds of Buckingham Palace but does not speak. In The Royal Collection she plays a larger role and is filmed in the first episode talking to Mr Lloyd in the picture restoration department in St James's Palace.
Mr Lloyd's best known predecessor as Surveyor of the Queen's pictures was Anthony Blunt, sensationally exposed and disgraced as a Soviet agent. Does his name crop up in the series?
Mr Csaky smiles coyly. 'There were,' he says, 'certain rules.'