These are valid gift vouchers from Stanley Gibbons stamp shop.
We found them while clearing my Father-in-laws house, he was given them as gifts but never spent them.
I have checked with the company and though old they are still valid, I have included the email from them to show this.
They need to be used in store or by purchasing through their catalogue.
I just found another £50 so we are now up to £150 in vouchers.