BoS also had Dick Place top of the table at this time last year, with a five-year average of £1.5M: http://www.bbc.co.uk/news/uk-scotland-scotland-business-16348190 In the twelve months since then, according to Zoopla, just one property has sold in that street in 2012, for £850K. In 2007 (the year which dropped off the moving average between 2011 and 2012), six properties sold at an average of £1.1M. And yet, according to BoS, that five-year moving average went up by £200K.
You might argue that with such small sample sizes, a minor difference in the data selected can make a big difference to the result. Nonetheless, it only takes a few minutes to compare the BoS' figures to Zoopla's for the top ten streets; in all cases the BoS' figures are higher than Zoopla's, and in the majority of cases they are much higher.
If Zoopla and BoS are both working from the Register of Scotland's data, why the discrepancy? (The cynical amongst you might suggest a possible link between this, and the fact that HBOS nearly failed because of their poor property loans. I couldn't possibly comment.)
(One last detail: the time period shown on the BBC web site for the five-year average to 2012 is actually six years. I'm crediting that to a typo by the BBC.)