Yep, I agree with Stewart - genuine 1950s Heuer Datemaster, possibly the immediate precursor to the 6126 that just carried over into the 60s, as shown in this 1961 catalogue:

If you look closely, you'll see that Barbara's watch has the same hands as the watch pictured. Looks like a bit of damp has got in through the crack in the plexi and affected the dial, plus there is a little surface corrosion on the case - the case is steel so can be cleaned up pretty easily, but refinishing the dial is a personal decision. One to weigh up, we've seen some pretty bad redials but then these aren't as "complex" as some of the dials from Heuer.

A similar version in gold-plate was on eBay recently (you'll need an eBay account to view, as it's a completed listing): http://cgi.ebay.co.uk/RARE-VINTAGE-HEUER-DATEMASTER-AUTOMATIC-MENS-WRISTWATCH-/120685310503?pt=Wristwatches&hash=item1c1967b227

So, to summarise, an automatic Heuer Datemaster, likely to be from mid- to late-50s. That's probably about all I can tell you I'm afraid Barbara, but please feel free to ask any specific questions you might have.