Applescript returning wrong month from Numbers

My Numbers table contains dates that are the the first of the month and I need to use the month name in a script. If Cell B2 contains a date, entered as "1 May 2019" without the quotes, the following AppleScript returns "April" rather than "May".

activate application "Numbers"
tell application "Numbers"
	tell table 1 of sheet 1 of front document
		tell row 2
			set x to value of cell 2
			set xx to month of x
		end tell
	end tell
end tell

Logging x shows that the actual date/time value in B2 is an hour before midnight

get value of cell 2 of row 2 of table 1 of sheet 1 of document 1
		--> date "Tuesday, 30 April 2019 at 11:00:00 PM"

So I'm wondering why this is, and what is the best way to avoid the problem. Putting

set x to value of cell 2 as date

doesn't help.