Thanks Peter, I will look to format my SD card as you've described.
In the mean time, something I forgot to mention:
Initially when connecting my shield's Vcc to the Uno's 5V pin to complete my connections, the Uno board's lights would die. This surprised me, but I thought the Shield might have been drawing too much power (my Uno takes power through the USB port only, with no additional supply), so I wired a 3x AA battery pack to the Shield, but used the two Uno ground pins to complete the circuit. Could this have caused the damage?
Or could initially trying to draw the Shield and Uno power from just the USB port have done the damage?
Further info:
Connecting the Shield to the 3.3V Uno pin with just the USB supply does not cause the Uno lights to die.
And, powering the Uno board with a DC 12V supply to its power socket in additon to the USB connection does NOT prevent the Uno lights from dying when I wire up the Shield to the Uno 5V pin.