The tune is given in Claude M. Simpson's The British Broadside Mallad and Its Music (1966), taken from William Ballet's Lute Book (16th. century).  It was current in the early years of Elizabeth I's reign, and was named as tune for two other songs in a MS of 1566 or earlier.  A midi can be heard (vocal line only) via the  South Riding Folk Network  site:

Lusty Gallant