A good used Jensen Interceptor half shaft slotted nut, part number CT5076
The item is used and about 50 years old so there will be some age and use related wear (see pictures) but this is still good for many years of service.
At the time of listing you can get aftermarket parts from Robeys for about £11 ex vat but if you wanted a good used original part at a fraction of the cost of aftermarket one (probably made from Chinese steel) then this item might be for you.