I note a gift and sale back by the donee to the donor is considered unobjectionable in the link below (subscription needed) to avoid the 3% SDLT surcharge (for the donee on his new purchase), so on that basis a gift & gift back seems OK too.
See also this from link below:
In general, the purchaser must have disposed of either the freehold of a previous main residence or a lease of their previous main residence which had a term of more than 7 years when it was granted.
The disposal of the previous main residence does not have to be by way of sale, although that is likely to be the case for most individuals. For example the property may have been gifted to someone else or transferred under a court order as part of a divorce settlement."
It could be sold back for £1 of course. I note TD's comment about exchanges and I do not think that would be relevant as it's the same piece of land and not a true exchange (and it's unenforceable in any event).