Although retail sales on the street are looking pretty glum at the moment with retailers closing their doors by the week it's nice to see a report that sales of Blu-ray movies are up, by an incredible 400%.

The British Video Association have reveled (in a chat with pocket-lint.co.uk) that 1.5 million disk were sold in December. This is great news for Sony, the format and entertainment sales, but lets look try to examine why such a huge jump.

Blu-ray is a new(ish) home movie format, one which had a vicious and fairly long battle with Toshiba's now defunct HD DVD to be the successor to DVD in the home, so 2008 was the first Christmas that consumers had only one high-definition format to choose from, a relief for many I'm sure. Couple this with the fact that the price of the players are coming down to that which consumers beyond the film fanatic are willing to pay and the number of Blu-ray players in the home starts to increase.

HD TVs are also dropping in price and you can currently pick up a decent 1080p TV for well under £1000 if that's too much a decent "HD Ready" can be bought for as little as £300, this together with good sales of the PlayStation 3 which can play Blu-ray movies means that the high definition world is hitting more and more homes, probably by the week.

Now what was the best selling disk on Blu-ray in December, well no surprise to hear it was The Dark Knight (selling nearly 300,000) which was not only one of the more anticipated moves of the year but also one which many people would have wanted on the high-def format, summer action/sci-fi films are what will sell the format.

With all this in mind it's no wonder that sales of the Blu-ray disks are increasing at such a fantastic rate. Don't get me wrong I love Blu-ray and have the full high-def set-up and have enjoyed many films (WALL-E and The Dark Knight are particularly good) on the format, and I hope this surge in sales continues and eventually overtakes DVD, roll on Quantum of Solace it'll be great I'm sure, but it's not really a surprise is it?