(2nd part):
Moving up one stage further, we arrive at documents which can only be certified by a 'notary public' or a solicitor. These would include any situation where an oath has to be sworn. (e.g. if you're trying to sell your house and you need to make a legal declaration of where the rights of way are, you will have to draw up a plan of the rights of way and then swear an oath that the plan is correct. The notary public or solicitor will then certify that he has seen the plans and that he has heard you declare the oath relating to them).
Beyond this are documents which can only be certified by a solicitor (and not a notary public). There are also documents which can only be certified by the Lord Chancellor and even some which can only be certified by the monarch!
So, unless we know what type of documents are involved and what type of 'certifying' is being done, it's impossible to give a 'yes' or 'no' answer to your question.
Chris
(Just a note to Grunty. People who've retired from any of the jobs on the 'passport list' can continue to countersign passport applications. This bit appears at the end of the list: "Or persons of similar standing to the above, working or retired, are acceptable as countersignatories" :
http://www.ukpa.gov.uk/faqs/faq.asp?intElement=454 ).