never heard of this,any good?

i saw this on tv in the early 80s - i was suprised that the film was made as late as 79 as back then films took longer to get to the small screen. i was off sick from school and it was on in the afternoon. i remember it being really good, but that was over 30 years ago.
i am assuming its the right film (in one scene they look at a row of shops and they are all owned by relatives of the David Niven character, is it that one?)

It was often shown on UK TV under an alternative title - The Biggest Robbery

It's on talking pictures on Sky just now. It's a jolly good romp to be honest and it's got a great cast. It's dated of course but well worth a watch. By the way, the shower scene is in!