Been trying to find some of these, and am so far at a loss…

I recently bought myself a new stove for camping/hiking (An MSR pocket rocket to be exact) and figured that while I intend carrying a lighter or matches separately when I intend using it, some form of backup to ensure I can light it may be useful – hence looking for matchbooks as something flat that should fit inside the plastic case alongside the stove unit and always be there if needed, unlike other separate sources, which while generally better and more reliable, can be forgotten or misplaced…

The only ideas I have gotten so far is ‘try restaurants and hotels’ which seems a bit cheeky, as surely there should be somewhere I can pick up a couple of matchbooks online (ideally in the UK)…

Any ideas?