Any difficulty using non-chip credit cards in England?

You shouldn't encounter many problems. In the UK have found that some supermarkets will only accept chip cards. Other than that all other merchants accepted non-chip cards.

We used cash in London, it's cheaper to use cash than a credit card. Most credit cards attach fees to every international transaction. Taking cash out of an ATM machine usually has a very small fee attached to it, and we would take 100 pounds out at a time for all of our misc expenses. The only time I had trouble was with my American Express Blue credit card. Even though I called them in advance before we left for London, when I tried to make a 65 pound purchase on it, they said it requested a phone call. I used a different credit card and it went through. And the AMEX Blue card is a chip card, strangely enough.

Last May we used our CC at petrol stations fine, although I read that it could be a problem, it wasn't for us. Asda's was unable to process our Capitol one or Am exp, they said it wasn't because of the lack of a chip, but it didn't work none the less. Otherwise we had no problems using our CC w/out any chips in the UK.

I was in London and Manchester last week.
I would say that as long as you are in a touristy area, it should be easy to use an american visa card. Otherwise, you may need a card with a chip since some places (even Tesco grocers..) dont have a "magnetic stripe swiper thingy". Some only have a chip reading machine that you slide the card into lengthwise and it only reads the chip and you type in the PIN. Luckily, my husband's British and retains his UK Barclays Mastercard for UK trips. There were a few places in Manchester (not touristy!) that wouldnt take my wells fargo visa card. So sad, had to use his. :)
I usually go with a couple hundred pounds cash and try to avoid using cards as long as possible.

OK, this doesn't apply to the UK, because I'm currently in Belgium... but this is my first trip to Europe where I've been inconvenieced by not having a chip, either on my ATM or credit card. It hasn't been a major problem, and it has only occurred well off the tourist trail, but I've encountered merchants, kiosks, petrol stations and ATMs where my cards would not work. Is this a fluke or a sign of larger things to come, I don't know...

In my experience Holland is the worst "offender" when it comes to this. The only merchants that will accept non-chip cards are hotels. Not even the ticket windows at the trains station will take them, and the new hi-tech lockers that have been installed in the stations over past year, only accept chip cards. At the entrance of the Albert Hiejn supermarket behind the Royal Palace in Amsterdam, there is a large sign in English explaining this, yet there will always be a another American ahead of me in line that didn't notice it:)

When I was there this time last year I had no problem at all using my non-chip Canadian MasterCard & Amex; the only placed that "sighed" was local pub near Tadcaster, Yorkshire. I do know you cannot use them when buying or picking up rail tickets from an automatic machine. Also, I had no problem using my non-chip ATM card either.