It employs around 120 staff to test and hallmark precious metals, particularly gold, silver and platinum.

It is the largest assay office in Europe, and possibly in the world, having hallmarked 15 million items in 2007.

The Birmingham hallmark symbol is an anchor.

This symbol was chosen when Birmingham and Sheffield were lobbying Parliament for the right to establish their own assay offices in 1773.

Both delegations stayed at the Crown and Anchor on the Strand whereupon the Sheffield hallmark became the Crown and the Birmingham hallmark, the Anchor.

There were suggestions that hallmarking was unnecessary and that traders should be free to sell gold, silver and platinum without each item being hallmarked.

However, the jewellery trade, supported by consumer groups, argued that since precious metals are always alloyed with base metals, compulsory hallmarking was necessary to prevent the ratio of base metal being fraudulently increased.

The Business Minister, Mark Prisk, has since announced that compulsory hallmarking will remain.