I use a meter that I got from Maplin, it records, voltage, amperage, wattage and Kilowatt hours. It's made to plug into a 13amp socket and has a 13amp socket on the front. I have checked it against known loads and it is accurate.
I was very dubious about the 1amp label as this would equate to 240watts, which would be high even for a CRT monitor. A TV on standby equates to around 5watts