function swapPhoto(photoSRC,theCaption,theStrapline) {

if (document.getElementById("caption")) {

	var theImage = document.getElementById("mainPhoto");
	var displayedCaption = document.getElementById("caption");
	var displayedStrapline = document.getElementById("strapline");
	var imgFolder = "pics/";
	displayedCaption.firstChild.nodeValue = theCaption;
	displayedStrapline.firstChild.nodeValue = theStrapline;
	theImage.setAttribute("src", imgFolder+photoSRC);

    }
  }