The land registry does not list "transaction fees" and neither do auction houses. If the land was indeed purchased for a large amount of money, the buyer (who is now the seller) would need to have purchased it... either in cash, or with a mortgage. There's no mortgages outstanding for the company (per companies house) and the company has no money.
I'll be charitable and assume you're just a fool: you've been played by your property agency partners, and the "member of your team" is of course, I'm sure, the person who provided the valuation from their "independent" valuer (because they're the property expert after all).
You can go on rightmove or an auction website right now and see comparable land available for <£100k. The basis of your defence was that of course the land is worth a lot because land in the UK is worth a lot but that's just not true, the only place where parking spaces sell for more than £7,000 is in London: in 75%+ of the country, you could buy 1 acre of land for £7,000.
The value of unused land for sale is a function of the amount of realisable value, for example, if there is a piece of land with planning permission for a 5 bedroom house in an area where a 5 bedroom house sells for £1,000,000, the price of the land would be something like £1m - (cost of building a house) - (some adjustment for the risk borne by the builder which becomes their profit), e.g: £500k.
If your 1.72 acres of beach front land is worth close to £2,000,000 that would mean there is much more than £2,000,000 realisable value for an owner of the land. Please, think through how you could conceivably realise millions of pounds of value from a piece of land that you are unable to build on.
Land in the UK is plentiful, the reason that a small proportion of land here is expensive is because only a small proportion of land is suitable for development and has permission for development. You could buy acres and acres of land anywhere in the UK for the price of 1 months rent in London... because the land is undevelopable, because you'll never get permission to develop.
The idea that an acre of beachfront is worth millions, when it has much less than a million worth of realisable value, is absurd. You're a business man, write a business case for this land.
If £7,000 was a "transaction fee" then is this other auction, with a listed sold price of £130,750, a transaction fee of £130k for this piece of land? And if so, is this land worth (130,750 / 7000) * 1,900,000 = £35 million?