Gervin ale and Nottingham are the same but your Munton's Ale yeast may be a different strain from the Munton's Gervin ale yeast sold here in the UK. Gervin/Nottingham is/are both pretty attenuative and gives a dry finish that some people describe as tart. Doesn't sound like yours.
There are three different Munton's yeasts (available here in the UK) that may be causing confusion? Munton's Active yeast and Munton's Premium Gold yeast are both sold in 6g packs and found here:http://www.muntonshomebrew.com/category/yeasts-and-other-products/
And thirdly Gervin yeast, sold in in 11g packs, and found here as GV12, is widely believed to be the Nottingham strain:http://www.muntonshomebrew.com/other-products/gervin-yeast/
I'm sure that all three are different, they behave differently.
Gervin GV12 behaves like Nottingham and is used by many home brewers in the UK, it's very cheap, about £1.50 for 11g.
Munton's Gold is pretty neutral but has a touch of fruitiness, it attenuates less than Gervin, low 70s, and flocculates much more slowly. This yeast seems fairly popular here, costs about £1.75 for 6g. The small packs are off putting in the modern market though, I'm sure they would sell more if they up-sized them.
Munton's Active yeast is very cheap and it does not convert maltotriose - Munton's recommend it for use with cheap extract kits where simple sugars are added to make up the fermentables - though it can work well in low gravity AG beers like milds, to leave some body and sweetness.
I've recently tried MJ Liberty Bell yeast, and I like it. Would be interested to know where this yeast originates from, but the marketing chap I bumped into recently from MJ wasn't giving anything away. He did say one of the MJ range was re-packaged Nottingham though. My guess would be M42, can't see what else it could be.