When 'The Story of Light Entertainment was shown on BBC4 earlier this year I downloaded it and it expired after the usual time period. I noticed that it was shown again last week and I tried to download it to watch but the IPlayer has advised that as the programme has already expired on my laptop it cannot be downloaded again.

I recognise that one cannot download a programme a second time during its existence on IPlayer. What I did not appreciate was that IPlayer also blocks you from re-downloading when a programme is repeated as a entirely separate run months later.

How far back does IPlayer go in blocking like this? If it is indefinitely it could prove a real impediment if a show was repeated two or three years later and it still tried to block by reason of a long-ago download.

It is a bit hit an miss, but sometimes if you download in a different format, you seem to be able to still do it e.g. try download as a windows media file instead (you may need to upgrade your windiows media player).