A1 ENGLISH TEST EXPIRY DATE

My now wife came to the UK on a fiancée visa and of course had to demonstrate A1 English speaking and listening. She had her test at Vantage Siam Bangkok who use the Bulats test and passed first time. Whilst it hasn't been a problem for us, I have just found out that test result is only valid for 2 years and was wondering if UKBA would refuse to accept certificates which are out of date? - Finding out the hard way could be expensive and disruptive of course

Hope the warning helps someone out and sorry in advance if the topic has been previously covered.