IHT PET and bridging loan 13yrs later

[p2c]

Hi all, any inheritance tax experts in the house?

About 13 years ago my mother gave me a sum of money as a PET which being now over 7 years ago has matured and will be tax free when the time comes, however the slight snag is she is moving into a retirement flat and would really need a 75k bridging loan between buying one property and selling the other, now its obviously the right thing to do to help her out here, but that could be a very costly mistake if doing so invalidates the original PET as could it be seen by the inland revenue as her retaining an interest in the original gift if a chunk of it is loaned back?

If it is a problem, are there any creative ways around such a problem, at the moment the only ones i can think of is me buying the old house, but that will have stamp duty and possibly capital gains implications especially if brought at a discount. The other option may be for me to act as guarantee for a loan from a friend who also has enough in the bank to make the loan but that's very messy.

Thoughts?

[Ean218]

Surely if it is done formally, at commercial rates of interest, HMRC would not have any reason to be interested.