Helmet Advice

This seems to be a largely US ng but I couldn't find a UK equivalent so here
goes:

Just got back on a bike after a few years. Never previously worn a helmet
but having three kids changed my perspective. Anyway in my price range - up
to GBP30 or so - there are a couple of alternatives on offer at the local
store Specialized Chamonix and Met MaxTrack II (I'm sure I could order
another if there is a standout model). One of the reasons I'm asking is that
five years ago 'Which', a consumer magazine in the UK, did a survey of bike
helmets and a majority were not suitable for their intended purpose, ie they
did not adequately protect your head. So what would you recommend as a
suitable helmet for someone commuting 4 or 5 miles a day to work and back on
city roads?

cheers

dd