Archaeologists have unearthed the oldest handwritten documents in Britain - which include a reference to St Albans dating back nearly 2,000 years.

The wooden tablets, discovered during excavations for Bloomberg's new European headquarters near Mansion House in London, have been described as "the email of the Roman world", communicating business and legal dealings.

Among 410 tablets uncovered, 87 have been deciphered, including a contract from October 21, 62 AD, to bring ‘twenty loads of provisions’ from Verulamium – modern day St Albans – to London, a year after the revolt by Iceni queen Boudica.

They also include the earliest dated handwritten document in Britain, a financial record of money owed which bears the date January 8, 57 AD, and one archaeologically dated to 43-53 AD, the first decade of Roman rule in Britain.

Most of the tablets appear to have been trash brought in to use as a sort of landfill when Romans were building on top of one-time Walbrook River. Some legal documents, though, were concentrated in a small room — possibly the oldest law office in Britain.

All the tablets were originally coated in black beeswax, on which messages were written.

Sophie Jackson, archaeologist and director at independent charitable company Museum of London Archaeology (MOLA), which led the dig, said they had high hopes for the excavation at the outset but the findings "far exceeded all expectations".

"The tablets are hugely significant, they are the largest single assemblage of wax writing tablets found in Britain and what's particularly special about them is they are so early.

"It's the first generation of Londoners speaking to us," she said.

More than 700 artefacts from the excavation will go on display late next year in an exhibition space in the new Bloomberg building.

Before this discovery, the museum says, archaeologists knew of only 19 readable wax tablets from Roman-era London.