Detecting 'text' file type (ANSI vs UTF-8)

I wrote an application (a psychological testing exam) in Delphi (7) which creates a standard text file - ie the file is of type ANSI.

Someone has ported the program to run on the Internet, probably using Java, and the resulting text file is of type UTF-8.

The program which reads these results files will have to read both the files created by Delphi and the files created via the Internet.

Whilst I can convert the UTF-8 text to ANSI (using the cunningly named function UTF8ToANSI), how can I tell in advance which kind of file I have?

Seeing as I 'own' the file format, I suppose the easiest way to deal with this would be to place a marker within the file at a known position which will tell me the source of the program (Delphi/Internet), but this seems to be cheating.

Thanks in advance.