Camping mat (dble) for light guests (Kings Langley WD4)

10cm thick self-inflating Sea to Summit camping mattress. Quite hefty and starts off extremely comfortable but very gradually deflates overnight. Has a solid core so never gets totally flat. No problem for children or people used to the thinner camping mats. I haven't tested to see where leak is. There are instructions on Sea to Summit website. Originally cost over £200 and is still very clean so hope someone can collect very soon and test it.