First, Rachel Yankey rifled a left-footed shot against the woodwork and moments later Eniola Aluko's effort looped over goalkeeper Marisa Brunner but bounced back off the bar.
Aluko turned provider just before the half-hour mark, with a clever flick into the path of the onrushing right-back Alex Scott, who scuffed her shot under pressure from Brunner.
The Swiss looked comfortable on the ball and lively in attack, with Ramona Bachmann at the heart of all their best moves.
Shortly before half-time, she weaved her way into the box, but her shot was well blocked by Faye White.
And two minutes later, England went in front as Smith's effort was saved by Brunner but Williams followed up to calmly place the ball home.
Our job is half done - Powell
England's second arrived in first-half stoppage time as Smith exchanged passes with Williams and lashed a shot across Brunner.
With England seemingly happy to sit back and protect their lead, the second half was uneventful until the last 15 minutes when the Swiss attack started to put England's backline under some concerted pressure.
Noemie Beney's shot was tipped over the bar by Rachel Brown and Marina Keller headed wide from the resulting corner.
But England held on to secure a result that leaves them well placed to qualify for Germany 2011.
England: Scott, Stoney, Unitt, White (c), Chapman, Scott, Williams, Yankey (Clarke 89), Aluko, Smith, Brown
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