I have a couple of henley blocks on my incoming electrics board
located after the meter. The henley blocks have seals on them. (The
incoming electrics run through the meter, through henley blocks to the
CU)
I need to change my consumer unit, so I would like to open the henly
blocks up and connect the new CU tails.

Is it illegal to open these seals even though they are placed after
the meter?

Thanks in advance for your help,

Best regards

Mark Wilmott