var images = new Object();
images = {"/homepage-images/baby.jpg": "Baby being baptised", "/homepage-images/cross.jpg": "Cross against sky", "/homepage-images/abybaptism.jpg": "Archbishop of York baptising", "/homepage-images/abcpershaw.jpg": "Archbishop of Canterbury ", "/homepage-images/mosaic.jpg": "Jesus Mosaic", "/homepage-images/graffiti.jpg": "Lambeth graffiti presentation", "/homepage-images/stayingalive.jpg": "Young people in church"};
var n = 7;

var rnd_no = Math.round((n-1)*Math.random());
var alt;
var src;

var counter = 0;
for (var key in images) {
    if (counter == rnd_no) {
        src = key;
        alt = images[key];
        break;
        }
    counter ++;
    }

document.write('<div id="large-image">' + '<img src="' + src + '" width="450" height="196" alt="' + alt + '" />' + '<\/div>');