5 List BOB

[Jace]

Full metal water bottle (at least 1L), knife, lighter, survival blanket, rations

[Binnie]

I agree with this list,

Metal containers can be found litereally anywhere, and some kind of filtraition for water can be fabricated easily, like most other things, with a multi tool or knife at worst.

[Timelord]

As Binnie said, a lot of stuff can be found easily in the UK. Plastic bottles, sheets, hard shelter. Dry season or wet season, warm or cold all makes a difference to the BOB contents. For me it would be a quality mid size knife, firelighting kit with tinder preferably, water filter set up, some first aid supplies and food. The rest will be supplied by the lateral grey matter between the ears, however little that may be, it is probably the most important and zero weight penalty multitool. TL.