I am discovering that there are many exceptions that prove the rule in the world of wine. Here are three of them.

1. For a start, you can't get a decent bottle of Bordeaux for £10 can you? Actually yes you can and what's more this one's on offer, at Waitrose, until the end of the month. Dourthe Barrel Select St Emilion 2005 is a blend of 70 percent merlot and 30 percent cabernet franc and cabernet sauvignon. Dry and rich, with under-ripe plums, spices, cedarwood and supple tannins, it's well balanced and needs food (good food preferably).

2. Those half-price bottles of wine in the supermarket are never worth the full-price are they? I think most often that's true but it's not the case with two Chilean reds on offer at Tesco from April 18. I couldn't believe the quality of these two Luis Felipe Edwards wines, especially since I tried some others from the same producer last year and wasn't impressed.

The wonderfully spicy LFE Estate Carmenère 2005 is smooth and jam-packed with brambles, cassis, liquorice and toasty vanilla oak. Carmenère, Chile's signature grape, is notoriously difficult to make well. This example is made well and is a steal at the offer price.

Almost as impressive is LFE Estate Cabernet Sauvignon 2005, a text book, hard-nosed, pencil-lead textured cabernet. It has lots of characteristic blackcurrant fruit and ample tannins with notes of tar, menthol and toasty, well integrated oak.

3. If a wine's from New Zealand's Marlborough region it must be sauvignon blanc musn't it? Not true, although a glance at most supermarket New Zealand listings might convince you otherwise.

But for proof the the climate in Marlborough is good for other varietals too, try Villa Maria Reserve Marlborough Riesling 2006. This wine is beautifully crafted, light, crisp, relatively low in alcohol, and on the dry side of off-dry. I think if I'd tasted it blind, I would have guessed it was German. It is full of flavour, grapefruit, lime and lemon with lots of minerality. The only problem is, to get the most out of this wine, it needs cellaring for five years or so. Wake me up in 2012 please.

Dourthe Barrel Select St Emilion 2005, £7.49 from £10.49 (until April 29) at Waitrose 16/20

LFE Estate Carmenère 2005, £3.49 from £5.99 at Tesco (from April 18 until May 15) 18/20LFE Estate Cabernet Sauvignon 2005, £3.49 from £5.99 at Tesco (from April 18 until May 15) 17/20Villa Maria Reserve Marlborough Riesling 2006, £12.99 at Tesco 18/20