Is this property income? Or a property business?

[Incredulum]

Mr X contracts with Y to purchase a commercial building belonging to Y and agrees a price of £100.

Y wishes to continue to occupy the building for one year after completion of the contract - effectively a sale and leaseback. No consideration is paid for this occupation, however the price of the contract for sale is reduced to £95.

1. Is this 5k rent?
2. On the assumption that it is not - which I think is the better answer - has a property business commenced. i.e., can X claim capital allowances on the purchase cost - which can then be offset against employment income.

[section 44]

If the £5k isn't rent (which I don't think it would be) wouldn't it be an in-kind premium for the grant of a one year peppercorn lease (assuming that a lease would be granted, if not then it would be licence)?