Are PowerGen plc shares issued in 1998 still valid?

Yes, shares issued by PowerGen plc in 1998 are still valid, provided they were never redeemed, cancelled, or converted into other securities. However, it's important to check the current status of the company, as PowerGen was acquired by E.ON in 2002, and its shares may have changed in nature or been replaced. Shareholders should consult with the company's investor relations or a financial advisor for specific information regarding their shares.