In an older house, if he touches the existing fuseboard, he may be obliged to upgrade it. But the owners, unwilling to pay for this expense, may encourage him to find an alternative, resulting in his looping the powerpoint into an existing circuit, rather than running a new cable back to the switchboard. This is obeying the letter of the law, rather than the spirit, and it certainly does happen.
Looks like an example of how the law might actually be making things worse.
Quite frankly, in a situation like that my attitude would be to ignore the regulations and do whatever I consider best from an overall safety viewpoint.
Those statistics at the top of the page look a little suspect to me. Electrical fires due to shorts/earth faults jumped from 13 in 1995/96 to over 800 the following year?
The corresponding drop in the "other" figures suggests that maybe the method of classification changed.