For anyone interested in an answer, I used an array to return:

• a Header
• a blank cell
• the arrayformula output

= { "Mins Elapsed"; ""; ARRAYFORMULA(IF(A4:A="", "", (A4:A - A3:A) * 24 * 60)) }

NOTE: For the array to result in a column, not a row, a semi-colon (;) must be used, not a comma (,) to separate the array values.