There are three possible issues here - copyright, trademark and passing off.
Taking copyright first, it is doubtful that a phrase of just four words would be covered by copyright. I think you are safe enough under that heading.
Turning to trademark, a quick search on the Intellectual Property Office website suggests that the producers of Ashes to Ashes haven't trademarked this phrase. If they had you would need to check in which classes it had been registered - you don't just register a trademark, you register it for specific classes of use. If they hadn't covered badges (class 26) or something similar (e.g. class 25 which covers clothing) you should be ok.
In this particular case, the word "Quattro" may also be a trademark. A quick search on the IPO website suggests, although a number of companies have registered the word, none have registered it in a relevant class but you should check for yourself.
The final issue is "passing off". The producers of Ashes to Ashes could argue that you are fooling the public into believing that your badges are official merchandise. I have no idea whether they would attempt to protect themselves in this way.
One other thing to beware of in this area - some large corporations pursue cases which they have little or no chance of winning in court, knowing that they can intimidate small businesses into giving in. You will run out of money before they do.