There are a number of issues here.
Issue Number 1 is that most financial institutions, including credit card suppliers, make regular returns to credit bureaus. Subscribing credit institutions can view a summary of customers' previous credit records when an individual, in the future, applies for further credit. It will be quite easy for these institutions to view this person's payment (or non-repayment) patterns in the future. The phrase "impaired credit record" springs to mind as a likely future description springs to mind.
Issue Number 2 is that these financial institutions will, most likely, register judgement against the individual. The Judgement may be published in one of the appropriate gazettes, or indeed in the public press. A judgement mortgage may, in certain circumstances, be registered against the property or properties of the individual. The judgement mortgage would rank behind the primary mortgage charge, but would sit there nevertheless.
Generally, it is the primary mortgage holder that causes a property to be sold.
It is not a good idea to ignore financial institutions. This happy wanderer should establish contact immediately, and set up standing orders to service the various banks, etc.