As well explained by this answer, I know the usual confusion among the previous cession in perpetuity of Hong Kong versus the lease of the neighboring New Territories.
For all effects, China got the return of both of them as established by the Convention for the Extension of Hong Kong Territory of 1898. So, despite the series of unequal treaties, put in perspective this one could be considered at least a visionary deal as it has given a dated timeline for the devolution not just of the New Territories, but of Hong Kong as a whole. (That is, in effect this treaty not just was better, but also helped China to peacefully revoke the "perpetuity" of the two previous unfair treaties).
It is almost impossible that someone alive at 1898 (and grown up enough to influence in the sign of the treaty) could be still alive 99 years later, at 1997.
But the negotiations between China and the United Kingdom started way before the actual return/handover of Hong Kong (at least since 1971, when PRC obtained its seat in the United Nations).
It is also unlikely that anyone exerting any influence at that Convention of 1898 would still be alive at the 70s, but there was such a person? (In any side, British or Chinese)
In positive case, who and what did he/she/they said about it?