The premise of this inoffensive little film is that Guinevere Pettigrew (Frances McDormand) is a terrible nanny who cannot get a job in London just prior to the second world war. When her employment agency refuses to help her any more she overhears a telephone conversation about sending someone over and steals the caller's card from the desk. Dishevelled and starving, Guinevere races round to the apartment of Delysia Lafosse (the ever enchanting Amy Adams) before the agency can confirm. Rather than being in need of a nanny, aspiring singer and actress Delysia requires a "social secretary" to help her juggle her three boyfriends, which a reluctant Miss Pettigrew is in no position not to help her with as she so desperately needs the employment.
It's impossible to talk about this film without mentioning the accents, so I'll get that out of the way first. They're ... "interesting" to say the least. McDormand tries, but she's very obviously trying and is very uneven throughout, which does take away from her subtle performance. Pushing Daisies' hero Lee Pace plays one of the boyfriends and for the most part he's strangely passable but he slips occasionally too, but I was rooting for him in every sense (both his character and his performance to be successful) so it doesn't really matter. Adams is busy doing what I suppose is a Marilyn Monroe impression but ... sometimes it sounds like she's spent so long listening to the other Americans butcher the English accents she decides to have a go herself 
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In a strange way all of this actually suits the tone of the film, which is very silly indeed. There's pretty much every kind of humour you can cram in - farce, slapstick, innuendo, visual humour, one-liners, etc. - there's a little bit of everything. The dramas are completely inconsequential and far from unpredictable, but it is all very watchable. I hate the word "frothy" to describe films, but if ever one could be described as that (in terms of something nice, yet unsubstantial) then this is probably it.
The acting is all played in the right spirits, Adams is ridiculously cute as the slutty actress and McDormand plays straight against Amy and her bevy of men very well. Mark Strong is one of the boyfriends and has a bit of fun with it, Ciaran Hinds adds a rather useless but ultimately sweet subplot with McDormand and Shirley Henderson is shackled by having a 2D character that she wasn't able to inject too much life into.
This reminds me of Leatherheads, in that it doesn't aim too highly and doesn't miss, except this one succeeds in what it's trying to do on a much more consistent basis. It's continually amusing and occasionally laugh-out-loud funny, the sets and costumes are lovely to look at and it's edited at a very fast pace. Silly entertainment, but entertaining indeed.