Here's a small test to help understand how risk-averse a person is:
I have a coin. It's a fair coin, and the chances of it landing either heads or tails are exactly 50:50.
I will give you £1,000 if it lands heads, but if it lands tails, you will give me £1,000.
No deal? OK...
I will give you £1,500 if it lands heads, but if it lands tails, you will give me £1,000.
Still no deal? How about...
I will give you £2,000 if it lands heads, but if it lands tails, you will give me £1,000.
Oh, I forgot to mention, we can repeat this as often as you want / have funds to play.
Since it's a fair coin, somebody pretty tolerant towards risk might be tempted to go with the first offer, but anybody whose slightly risk averse would probably decline. Any of the subsequent offers, if played a large number of times, would be a positive outcome for the player, but they might still reject the game, depending on their attitude to risk AND their view on the impact of an unlucky streak.
If the impact of loss is significant, none of the above would be acceptable, but if the loss was OK, then which offer they take is a reflection of their tolerance for risk (or their ability to negotiate, once they've spotted the pattern of increasing offers
)
In the OP's case, they have £40K so could play 40 tosses of the coin before going bust. It would be interesting to see if they would commit to 40 flips, or whether they'd set a lower limit, which, whilst more likely to go bust (a shorter run of bad luck being more probable than a longer run) would indicate their views on the balance between risk/reward and capital preservation.
Nb. This is a thought experiment, not a KYC process!
VRD