A collection of letters featuring some of the biggest and most important names in the late 19th century art world are set to be auctioned at Whitchurch auctioneers Trevanion and Dean in Station Road.

The internationally important collection features members of the pre-Raphaelites including Dante Gabriel Rossetti and his brother William Michael Rossetti; Sir Edward Coley Burne-Jones, George Frederick Watts, among others.

The series of letters are all written to members of the Ionides family, a famous dynasty of British art patrons and collectors of Greek ancestry, the majority of which are addressed to Constantine Alexander Ionides (1833-1900) who is most well known for his bequest of more 1,000 pictures.

This series of letters to the Ionides family gives us a fascinating insight and often revealing glimpse at the sometimes unknown relationship between patron and artist.

Auctioneer Aaron Dean said: "When we first started transcribing the letters it was just magic to see the type of dialogue that had been going back and forth constantly between patron and artist.

"In this instance Ionides is kept in touch at every stage of the process, often suggesting subtle changes here and there, it is fascinating to see how much influence the patron had on the finished article."

He points to the Dante Gabriel Rossetti (1828-1882) as particularly interesting. Rossetti was a founder member of the Pre Raphaelite Brotherhood, a controversial group of revolutionary young artists who opposed the dominance of the British Royal Academy which championed a narrow range of idealised or moral subjects.

But even rebels like Rossetti had to pay the bills, as Aaron explains: "Among the collection there is a letter written by Rossetti to Ionides, in which he is proposing to paint a picture for him where he sets out the dimensions of the intended painting and he quotes 700 hundred guineas (approximately £300,000 in today's money).

"He then goes on to state that ‘Mr Graham paid me 800 guineas (£331,000 equivalent in today’s money) for ‘La Ghirlandata’ (now in the collection of art at The Guildhall Art Gallery, London) 1050 guineas (£435,000 equivalent in today’s money) for Beatrice (which sold at Christies in 2012 for more than £2 million) and 1150 guineas for ‘The Blessed Damozel’ (£476,000 equivalent in today’s money)."

He added that he letters unearthed not only provide an insight into an exceptionally important art collector of his time, but also the subtle and often unknown relationships between artists and their patrons in the late 19th century.

The letters will be up for auction on Saturday, Saturday 15.