Geordie and Wherry are both made by Muntons and are notorious for sticking around 1020:
http://www.muntonshomebrew.com/other-products/other-branded-homebrew-kits/
I find that use of a teaspoon or two of Yeast Enhancer helps prevent sticking and/or use an alternative yeast, as suggested. The Wilko Gervin Ale yeast is a re-branded Nottingham yeast and is very good. Wherry is very nice if you can prevent it from sticking.
http://www.muntonshomebrew.com/other-products/other-branded-homebrew-kits/
I find that use of a teaspoon or two of Yeast Enhancer helps prevent sticking and/or use an alternative yeast, as suggested. The Wilko Gervin Ale yeast is a re-branded Nottingham yeast and is very good. Wherry is very nice if you can prevent it from sticking.