Smallholding growth

In the mid 1970s my client and his wife purchased a piece of land for £5 000. This has been used since then as a smallholding and at times up to 75% to 80% of the produce was sold the rest being for personal consumption. Two-thirds of the land was sold a few years ago and as the clients are now in their 80s they are now thinking of selling the rest of the land; I understand that there was only a small sale of produce in the last twelve months.

Although the land is in a rural area there are residential properties on either side and my client seems to think that with 'hope value' the half acre could be worth up to £100 000. Would it be better to make a sale before or after 5 April 2008 and is there...