Selenium xpath - issue locating WebElement using contains(text(), 'somevalue')

I've recently encountered an issue where my xpath should be easily expressed as
xpath=//div[contains(text(), accountId)]
but this did not work. I thought I'd share the problem here.

I am trying to identify

<div class="your-account-info" style="background-color:blue;">

  <span class="hidden">Your account number: </span>

  123456789

</div>

so as xpath of 

//div[contains(text(), '123')]

should work, but doesn't. 

What does work 

<div class="your-account-info" style="background-color:blue;">

  matt was here

  <span class="hidden">Your account number: </span>

  123456789

</div>

using an xpath of 

//div[contains(text(), 'matt')]

will return the object.

Conclusion

So it appears that text() within xpath identification will only get text up until the start of the next tag.. which is limiting.

I am not sure of a workaround yet, but will post one as soon as I've answered it.