BBC2APK is a free software tool (for running on Windows) which can create an Android Application (APK file) from a BBC BASIC program (BBC file). Its main features are as follows:
Create a suitable directory (e.g. C:\Program Files (x86)\BBC2APK\) and save the file there. You will need administrative privileges to save the file and when you execute it for the first time (in Windows™ Vista, Windows 7, Windows 8/8.1 and Windows 10 with UAC enabled use 'Run as administrator'); however it can be run from a normal user account thereafter.
You should, of course, thoroughly test your program using the Android edition of BBC BASIC for SDL 2.0 before creating an APK, to ensure that it is fully functional and compatible with Android.