The fastest growing group of prisoners in the UK are of the older variety.
I don't think they account for a vast number of people but as a recent TV documentary showed they do pose issues for the prison authorities.
This is nothing to do with marketing but it is an amusing, a bit sad, but hugely entertaining programme. If you are in the UK you can probably watch it on one of the catch-up channels.
Here is the press release that accompanied the programme's release. Dick Stroud