I have seen one such case with a success.
Look for Feb 2014 - Naturalisation Application Timeline pg 9. Quote from that
'by techie_09 » Fri Mar 28, 2014 6:08 pm
Eligibility criteria: 5 Yr (HSMP + Tier 1) + 1 Yr ILR
Language criteria met (UK degree, exempt countries, PBS used documents, NARIC, or B1 test): Expired IELTS Test + LIUK
Current nationality: Indian
Method of application: NCS Croydon
Council name if NCS used: Croydon
Date of application: 07 Feb 2014
Payment method CC/DC, Personal cheque, Bankers cheque etc: Credit Card
Date of receipt by UKBA: 10 Feb 2014 (Tracked Confirmation)
Date of aknowlegment: 12 Feb 2014
Date of debit or clearance of fees: 12 Feb 2014
Date approval received: Spouse + Child received on 27 March (letter dated 23 March). Mine arrived on 28 March (letter dated 23 March)
Date of ceremony: 30 April 2014
Note: I have successfully met the English language requirement using my expired IELTS certificate which I used during my initial HSMP application 6 years ago.
Good luck for others who are waiting for approval letter. You will also get your letters soon.'
Pls note - I am in no way recommending you apply with a expired certificate. I had to give PTE academic and Life in the uk