The nominal value is just an accounting fiction that has nothing to do with the actual market value of the shares:
http://www.completeformations.co.uk/companyfaq s/shareholders/nominal_value.html
A deferred share is a share that is last in line behind the common shares in terms of receiving dividends or getting paid off in a liquidation. For a healthy firm the deferred shares will have value; you'd get worried if the firm got into financial distress (as you are last in line to get paid, if there's anything left after paying off debts).
In no circumstance does the nominal value of the shares come into play in determining the actual (market) value of the stock.