Del was a multi-millionaire business man for several years and therefore would have been in the highest UK tax paying bracket. As he had been evading tax for all that period he would almost certainly have owed vastly more than just £48,000 pounds to the Inland Revenue.
When Del is on the Television program "Goldrush", the camera is reflected in Rodney's TV when Del is asking him a question.
When Rodney and Cassandra are dressed up, Cassandra says, "My boss can't stand late parties," and walks off, a boom mic follows her and can be seen in the top right corner of the screen.