This is a representation of Gourock's coat of arms on a lamp post outside the Gamble Halls, Shore Street, Gourock. It combines the arms of the Stewarts of Castlemilk and the Darrochs whom I've written about in a previous post.
Gourock was created a burgh in 1694 and this is shown by the castellated top of the device. As you look at the picture, the left side is an adaptation of the arms of the Stewarts of Castlemilk with a hand grasping a dagger.
The Darroch side (right as you look at the picture) shows a three-masted ship with three oak trees. The name Darroch is supposed to be a form of the Gaelic word for oak 'darach'. This also includes a figure holding a club - a reference to an old legend of the warrior Macgille riabhaich (son of the brindled man) who brandished an oak club and was a fearsome fighter. Duncan Darroch was extremely proud of his roots and his links to the Macdonalds of Jura. You can read the legend of Macgille riabhaich here. The "wild man" was a popular symbol in heraldry.
Gourock's motto a combination of those of the two families - 'Avant' (Stewarts of Castlemilk) and 'Be Watchful" (Darroch).
This photograph is some of the detail of a beautiful fireplace what is practically all that remains of the main residence of the Stewarts of Castlemilk - it can be found at Castlemilk Stables in Glasgow. You can seem more photographs of this wonderful place and read some of the story of the Stewarts here on my other blog Shortbread & Ginger.
There was a time when decorated lamps showing town coat of arms like this were to be seen outside the residence of the local provost (mayor). Port Glasgow still has its town lamp which you can see in this previous post.