They changed the design after Breakergate. All breakers pre Breakergate are like the original breakers in that board: a thicker switch bar that is higher up the body.
As an aside, I personally think the new design is pants: there is less to get hold of if you have old, arthritic fingers to switch the circuit back on. It would have been better, in my view, to keep the same design but distinguish the new batch of breakers by fitting a different coloured rocker.
So, 6, 10 & 16A breakers need removing and checking to see that they are not on this list:
ELECTRIUM MCB RECALL NOTICE FOR THE ATTENTION OF ALL QUALIFIED ELECTRICIANS:
IN CASE ANY ELECTRICIAN OR CUSTOMER HAS SLIPPED THROUGH THE NET:
6A MCB and 10A MCB codes:
RIRA, RERA, RTRA, RARA, RCRA, SRRA, RHRA, SSRA, RGRA.
16A MCB codes:
RIRA, RERA, RTRA, RARA, RCRA, SRRA, RHRA, RGRA.
Please note, these codes represent the last four characters of the code printed on the side of the MCB.
As far as I know, these codes apply to all Electrium breakers, ie not just the Wylex ones, but Crabtree and Volex too.