IHT Practice Question 38 (Nathan) in OT 2017 F6 Notes

Can you clarify the answer to Q38 regarding CLT please? The answer says:

GCT’s in 7 years before 17/09/2010 was £350,000, therefore a gross transfer of £366,250 and Nil IHT as exempt after 7 years.
17/09/2010 PET, with a gross transfer of £40,000 and IHT of 16,000, as all £325,000 NRB deemed used (in the previous CLT) = 40,000 @ 40%

I am confused, as the NRB in 2006/2007 was £285,000, when the now expired CLT was taken. So wouldn’t just £285,000 be deemed as used, leaving a balance of £40,000 available for the PET in 2010/2011 tax year as the NRB band had then been increased to £325000?

I calculated it that the £40000 PET would have a nil rate IHT even though the previous CLT had used the entire NRB in 2006 because the new base rate in 2010 for the PET was £325000.

Please advise as I can’t find reference to this in any text.

Thanks so much