photographer mervyn o'gorman was 42 when he snapped the pictures in 1913 .
mervyn was known as an early pioneer of colour photography and used the autochrome process .
his teenage daughter christina o'gorman posed in red swimsuit at lulworth cove , dorset .
autochrome photography process used dye and starch to create the melancholy tone .
do you know who christina was and what happened to her ? email femail@mailonline.co.uk .