to any financial/ share dealing experts out there.

I've just uncovered and old share option certificate, from an old company I used to work for, (NYNEX cable comms), they've been taken over a few times in the last few years and are currently NTL,does any one know if this option is still valid?
it was issued in June 1995, who can I speak to ??
is it the case that once a certificate is issued it's valid until you exercise the option.
I've no idea about this sort of stuff, so I'm hoping one of you lovely financial types can help me out.

 

I would suggest contacting the Registar (should say who it is on the cert.)