Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

For the bolt i have highlighted on a corsa b 2000
Some say 18 and some say 19, what size spanner do i need to buy?

Also is it a drop neck spanner? with a 8mm normal spanner ontop to hold 8mm bolt

Thanks

Il check tomorrow mate can't remember off the top of my head

7mm and an 18 drop neck