The byelaw is this:
"No fishing weights made of lead may be used except those of 0.06 grams or less and those of more than 28.35 grams.
In angling terms this means that lead shot from size 14 to size 8 and lead weights of over 1 ounce can be used in fishing."
There are no byelaws governing the design of the lead weight, which means you can use a gripper weight if you wish providing it weighs more than 1oz.
Watch leads commonly used in sea fishing are very often used to fish a flooded or fast-flowing river.