I have referred to this before -- but for some it was difficult to get at, needing extra plugins etc. This is a relatively easy way to look at the reconstruction of the waxing and waning of the Welsh Devensian ice cap. You should be able to go straight to the video on Henry's web site.
http://henrypatton.org/2011/the-welsh-ice-cap
Note that this is the second of Henry's animations, for which he reduced temperatures by 0.2 deg C. the result of that was the introduction of an earlier expansion phase which culminated in a big and very ephemeral ice cap around 30,000 years ago. There is much debate about whether this happened or not. On the same web page you can see the other animation as well, which incorporates just one big expansion phase culminating around 23,000 years ago. In this animation the ice melts away very quickly, and is almost gone (except for remnants in the high mountains) by 18,000 years ago.
The other thing that will surprise many people is the great speed of ice cap development -- as in the case of the larger ice sheets, all you need is somewhere between 5,000 and 10,000 years to build a huge ice mass from scratch.
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