Photodynamic therapy (PDT) is used to treat some types of sun-damaged skin and low-grade forms of growths. A cream is applied to the skin, and the chemical in this cream is absorbed in to the skin and converted in to a 'photosensitiser'. This photosensitiser is fluorescent, meaning that it produces red light when blue light is shone on it. By measuring how much light is given off with a camera, the investigators can determine how much photosensitiser is present in the skin. Also, it is thought that more of the chemical is converted to the active photosensitiser if the skin is warmer, so the investigators plan to measure the temperature of the skin using a thermal camera. Light is shone on to the skin and this activates the photosensitiser, treating the problem area and leaving healthy skin intact. This research will increase the investigators understanding of how PDT works, and may help the investigators to improve treatment regimens so that they can be made more effective and better tolerated

Inclusion Criteria:

• 1. Patients presenting with superficial BCC or Bowen's disease (one or two lesions and diagnosed either clinically or histologically and untreated or having had no treatment for 4 months or longer) 2. Adult males and females, >18 years only 3. Capable of giving informed consent 4. Able to understand and adhere to protocol requirements

Exclusion Criteria:

• 1. Patients skin lesions have had previous treatment in the last 4 months 2. Unable to give informed consent 3. Known allergy to Metvix® 4. Known to have a light sensitive disorder 5. Pregnant, breastfeeding or planning to conceive