Dutch bricks?

These two bricks were found in the tidal muds at Grangemouth, Scotland and in the same location as a number of confirmed Russian stamped bricks.
Their ‘yellow’ colour, size (narrow) and visual composition suggest they may be early Dutch bricks.
One would appear to have the imprint of an anchor or perhaps it is a double-headed arrow design.
Does anyone recognise the brick stamp?
Is there date range for the import of these bricks to the UK?
Are there brick size parameters that help determine whether this is a Dutch import or not?
.
.
.
Below – Ian Suddaby found a similar one at the exact same location. Ian states – This is my example. It certainly has a similar ‘arrow’ at one end but a bit more cross-like at the other. Surely the same maker though. What’s the black coating? The other bricks don’t have that. The dates for the Russian bricks seem to be the 1840s to 1860s so that’s likely to be the date of the possibly Dutch ones too.
Vladimir Smirnov points out that The Hoganas Fireclay Works, Sweden often used anchor designs on their fire bricks. I have found Hoganas firebricks just 2 miles along the shore. However, the anchor bricks discussed here are not fire bricks and I think Hoganas only manufactured fire bricks.

Similar articles