I guess Helen and Pat are not up to date on milking practice, so probably can't. Pat runs the dairy. Helen runs the shop, which is more obviously a full time job, though I think the dairy is too really.
Businesses are valued on profitability, not just assets, unless they're bankrupt. There must be figures for turnover and profit, so they can say it will generate a certain amount over five or ten years. If I was buying a business I'd want to know how long until I expected to make my money back and go into profit (like on Dragons' Den!).