This is somehow complicated. It was said that the funds taken were in fiat currency and not Bitcoin, and then these funds bought BTC. Since the funds is converted to BTC, can the government trace the amount of BTC to each particular investor? If it can't be traced, then possibly monetary compensation will do. Returning the invested money to each Bitcoin, plus probably some compensation.
They cannot trace the Bitcoins directly to the victims since the victims did not invest Bitcoin, but it should not be that hard to return the money as they have probably already determined the total amount lost in the scam.
My point is that if all those 61k Bitcoins were purchased using the proceeds of the scam, then the victims should have ownership rights over those Bitcoins.
Why should the government own Bitcoin that was not purchased with its own money, maybe it should only be entitled to the remaining balance that no victims have claimed.
If the things is done with what I stated above, it would be a huge profit for the UK government and probably the Chinese government.
Yes, if they will keep it.
What if BTC dumps again?
You raise a good point, because what if the total value of those Bitcoins was already lower than the amount lost in the scam..
Would the government cover the deficit and compensate the victims for the remaining losses?

Of course not, so if they cannot refund the losses, they also should not be entitled with the gains.
In my opinion, the victims have the right to have their Bitcoin assets returned to them after all these years of waiting. This is their right and these are their assets, even if their value has increased tens of times.
They don't necessarily have the right to the Bitcoins because they invested fiat, so they may only be entitled to compensation in fiat.
I just brought up the possibility that they should receive the Bitcoin if the country making the final decision does what is right instead of being greedy.
From what I've read, if it uses Chinese law, then the profits are very likely to go to the British government. But I don't think it will be that easy --- the Chinese government also doesn't want to lose out in this matter, so it's possible that they will also ask for a share of the profits.
You mentioned profits, what particular Chinese law says that the government can keep the gains from the confiscated Bitcoins when there are identified victims claiming the amount they lost?
Just to clarify, I'm not saying the victims should be paid in Bitcoin, what I'm pointing out is that they should receive the proceeds from selling the Bitcoin at its current price.
Because obviously it's not hard to understand how gains are realized, only when a sale takes place.