[5] Although he appeared in many plays and had offers of more starring roles on stage, Doyle said he preferred radio "because it's more fun than the theater and more people hear you".

[6] Doyle carried his role of investigator Harrington from radio to the television version of Mr. District Attorney.

[1] His early theatrical experiences included being "shipwrecked in the waters south of Australia" after a ship carrying an acting troupe was hit by a typhoon.

[9] In the 1930s, he appeared in a number of plays in New York City, including Shadow and Substance, The Time of Your Life, Three Men on a Horse, Night Hawk, Within Four Walls, and Family Upstairs.

[10] In 1943, he was in a touring company of I'll Take the High Road, which had performances on Wednesdays but used an understudy in Doyle's place so that he could continue with the radio program.