Assuming that it was installed correctly in the first place and has not developed any faults, it will be no less 'safe' than when it was first installed.
The main sense in which some might argue it to be 'unsafe' is that it does not contain the RCD protection that is now required for all new/replacement CUs. To what extent that means it is 'unsafe' is a matter of opinion (the regulations do not 'require' it to be replaced with a modern one) - there are probably still millions of domestic installations out there which are similar to yours.
I suppose you could consider it analogous to driving a very old car which didn't have some of the modern 'safety features' (ABS, air bags, renforced doors etc.). Assuming all was still in good working order (as per when it was built), hence as 'safe' as it was when first sold, would you call it "unsafe"' or not? "Less safe than it could be today" might be a fairer statement.
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