Car requires jump start after standing for 2/3 days.Lights, dash, radio etc. all ok.Problem does not occur with daily use.

2 things come to mind. 1) the battery is on its way out. 2) there's a electrical short some place. An easy way to check for a short is to disconnect the battery be sure the doors are close and no electrical acc are on and see if there is a spark when you touch the battery with the end of the disconnected battery lead.