Intrigued office staff who had spotted the duck fluttering around a few weeks previously ventured out to find a nest containing around a dozen eggs perfectly positioned between the stalks of the low shrubs.
According to the RSPB mallards often choose less than perfect nest sites.
Indeed, with the nesting season in full swing the charity has warned people to be aware that all sorts of birds sometimes nest in very unexpected places including postboxes, rubbish bins, clothes-peg bags and even the pockets of jeans left hanging on the line.
Here at BBC Wales Nature that got us wondering whether any of you may have spotted nests in odd places.
Be sure to let us know using the comment form below or you can drop us a line with any photos via email if you prefer.
In the meantime, check out the Type Nesting website for more pictures of birds nesting in strange places.