David Jason's character visits the bank to pick up the share certificates left to him by a previous Master. Much to his surprise the bank manager tells him that these shares are now worth £500,000. The bank manager looks at the certificates, then at a screen by his desk before making the calculation very quickly in his head. Given that the certificates are decades old this is impossible. It would take a considerable amount of time to work out the new number of shares that the certificates would entitle the bearer to based on share splits and consolidations over the years. Also, the shares would be denominated in pre-decimal currency so they would have to be revalued based on the conversion rate at the time Britain went decimal. It would be a time consuming and painful task to decide their new value.