CGT on lease extension - Leasehold Reform

[LoTax4me]

The house I live in is divided into two flats. I live in one and the other is subject to a long lease but I have owned the freehold for many years. The leaseholder recently exercised their right to obtain a new lease on the same terms for a longer term under section 39 of the Leasehold Reform, Housing and Urban Development Act 1993. As a result I received a substantial payment. The base cost of the freehold is small. Do I have a CGT liability on the balance? Or can I claim that concession D39 applies (http://www.hmrc.gov.uk/manuals/cgmanual/cg71242.htm)?

[RMC]

ESC D39 does not apply, you did not dispose of a lease.
The CG calculation will be under the part-disposal rules: from the proceeds you received, deduct the following fraction of your cost of the lease plus freehold:-
proceeds / proceeds + market value of the remainder (=your own lease plus ½ freehold)

If the proceeds were no more than £20,000 and no more than one-fifth of the market value of the total holding and you did not make any other CG disposals, you could claim relief under TCGA 1992 s.242. Text available on the web.

[LoTax4me]

Thank you belatedly for your helpful reply. I've paid the tax, but at least I'm not left with a nagging feeling that I might have missed a trick.