Hi Richie,
An approximate date even for these pieces is very difficult with such sparse info. The Dicey Marshall dynasty lasted a long time and I don't yet have a lot of info on their trading details. All I can say for certain at the moment is the Bow Church Yard address precedes the Aldermary Church Yard.

Here are some dates I have found
Wm Dicey at BCY 1740-56
Cluer Dicey at BCY 1756-63
Dicey & Co at ACY 1754-64
Cluer Dicey and Richard Marshall at ACY 1764-70.

All this really tells us is that one or other was at Bow to 1763
and from 1754 Cluer was established at Aldermary.