Sincere thanks to all who contributed following my request for help in choosing a zoom lens.
I finally followed the advice of the majority and purchased a Pentax 55-300 from James at the Colchester branch of London Camera Exchange.
It is however, the DA-L model so has a plastic mount, which does concern me a little.
Up to now I am pleased with it, however I find the auto-focus sometimes plays up; eg. if I have focussed on something close then immediately try to focus on a more distant object, the lens "freezes", If I then change the zoom setting it will focus immediately.
Is this usual?
Regards, Fabson

My goodness, I didn't expect so many helpful replies. Thanks to all of you.

Available cash: £100-150.

Yes I have an FZ10. I suppose the lens is "faster" than affordable DSLR zooms,at full zoom, or am I wrong? My feeling also is that the Pentax images are "softer" and on long views depth of field is less.

My choices of subject matter are landscape, nature (flowers, insects, birds and animals),old buildings and village scenes.

Possibly this extra information may be useful in pointing me in the right direction. Many thanks.

Good day to you all from the Yorkshire countryside.
I'm new to Pentax having been weaned from film SLR with a digital bridge camera, with a very good Leica 12 times optical zoom lens.
The image detail leaves little to be desired but at 4mp cropping for print is almost out of the question.
Now I have the K20 with the kit 18-55 Mk11 lens, which just doesn't match the detail clarity.
I want a zoom lens, preferably around 50-200, with better glass than the kit lens, auto focus and compatible with the shake reduction (most important, I'm over 75!). Oh and one other thing, I don't have a lot of money.
When I read DPreview and other reviews I see a "lack of clarity" at full zoom, which worries me because I would buy a zoom lens to get the benefit of the long zoom.
Sorry about a long winded introduction. Thanks for any possible help.