Yeah typically the air rises over the Cotswolds or Pennines. When that
happens it cools, condenses and dumps its moisture as rain. Then when it
comes down the other side down hill to the Southeast, it warms up and there
is less moisture available for rain.

A similar effect called the Fohn effect occurs in Scotland. The air rises
over the Cairngorms and dumps its moisture. Then it descends and warms. The
stronger the wind the more pronounced the effect is. As a result the
Aberdeen area can be surprisingly warm and sunny when it is grey cold and
damp to the west.

-Mike

"danny (west kent)" wrote in message
news
Does a hundred miles or so of land really
effect
weather fronts that much after they've crossed 3000 miles of water?

Yes. Westerlies, particularly those that lack punch (think high pressure)
give very little rain.

Why is the south east so dry compared to areas only a few hours
drive away?

It is generally low in altitude....It's well sheltered by the land from
Westerlies. SW\ S are rare to the reasons I mentioned. We had a short
spell
of SW this Autumn\Winter and had lots of rain.