This is not fully true. If you remember, "Gridlock" is set in the future - and he wears his brown suit. And "Daleks in Manhattan" & "Evolution of the Daleks" were set in the past - he wore his blue suit. And in other episodes, he wore his blue suit in present-day AND his brown suit in present-day.
- Thanks for the help. I saw this online and thought it sounded fishy. I was having trouble fact-checking it from the images I could find on the web.