These are not programmes my children are going to insist on videoing to watch over and over again. And privately, the BBC admits that it has a bit of a natural history problem with the great man himself. For the spritely, superb Attenborough, 70 next year, has become so indelibly associated in our minds with this hugely successful TV genre, that it is hard to know who will or can follow him, when, inevitably, the trials of life mean he has to retire.
There is no one with his drawing power as a presenter; just having his name and presence on a programme guarantees instant attention from millions of viewers of all ages. It also helps persuade visiting American co-producers to part with their cash. Natural history producers say there is always one thing their American counterparts ask when they come over: can we meet Sir David?