Thanks Rich,
You were right about needing to convert the timestamps as now I can calculate the time differences properly: here's how I have done it (for anyone else looking for the solution):
Code:
Auction Started:
<?php
$result2=mysql_query("SELECT UNIX_TIMESTAMP(timestarted) AS FORMATTED_STARTTIME FROM table where item=$_GET[item]");
$FORMATTED_STARTTIME=mysql_result($result2,0,"FORMATTED_STARTTIME");
$date1=date("l-j-F-Y H:i:sa",$FORMATTED_STARTTIME);
echo "$date1"; ?>
Auction Ends:
<?php
$result3=mysql_query("SELECT UNIX_TIMESTAMP(timeend) AS FORMATTED_ENDTIME FROM table where item=$_GET[item]");
$FORMATTED_ENDTIME=mysql_result($result3,0,"FORMATTED_ENDTIME");
$date2=date("l-j-F-Y H:i:sa",$FORMATTED_ENDTIME);
echo "$date2"; ?>
and then using:
$diff=$FORMATTED_ENDTIME-mktime();
to calculate the difference in seconds.
Thanks very much for your help
Sami