I read the other day that there were two varieties of portcullis on the decimal UK penny. Considering how many of these I must have handled in my lifetime it surprises me that I hadn't noticed them before. I have taken photos of them and put them on my site - the link below will take anyone interested to the page.
No in 1995 and 1996 only type2 was used and in 1998 as far as I know their was a switch back to type1 and type2 was not used at all. All years before 1992 would have been the first type.
There are brass 3d varieties concerning the corners so I think the portcullises are worth checking out.
The Pennies must have been spotted before now but I only read about it the other day. It isn't in the 'Bronze Coinage of Great Britain' by Michael J Freeman because the coins of 1992 and onwards are copper plated steel.