IHT business relief using unlisted and listed shares

IHT business relief applies to unlisted shares (e.g. AIM) if they have been held for 2 years before death as well as on the date of death.  Alternatively, unlisted shares can be sold and then replaced by other unlisted shares and if the sequence of periods of unlisted share ownership adds up to 2 years before death then again business relief still applies.  However, if an unlisted share is replaced by a listed share (e.g., the AIM company re-lists on the main stock exchange) and subsequently sold to buy shares in another unlisted company, which is held for less than 2 years before death, does business relief apply?

Inheritance Tax Act 1984, section 107 (1) says "Property shall be treated as satisfying the condition in section 106 above if any other property concerned was such that, had the transfer of value been made immediately before it was replaced, it would (apart from section 106) have been relevant business property in relation to the transfer".  Does this imply that  the unlisted share must be sold for cash before the company re-lists on the main stock exchange and that cash used to buy another unlisted share?