Your Father must have an amazing collection by now, I hope he can share some history and knowledge of what he has with you. My father often shared with me and his collection came into my hands since my other siblings didn't care much for it. The 1808 date puts your 2 1/2 Guilder coin square into the Napoleonic War.
I have a few old silver Guilders somewhere but I have yet to share them.
I hope you can share more silver coins like these in the future @michelmake
Yes, there's quite some cool coins in his books. I have to really go through them next time I'm there so that I can share them here! Napoleonic war indeed! Interestingly my girlfriend who is a paintings conservator worked on a famous Dutch painting of the battle at Quatre Bras by Jan Willem Pieneman. They moved this huge painting from the royal palace in the Netherlands to the military museum where they conserved it. You can see it here all in action: https://www.nmm.nl/en/waterloocrossroads/