[1] The society was formed on 12 June 1893 during a meeting held in Mablethorpe.

The meeting came about from conversations held by William F. Baker and Joseph Coe with "prominent naturalists connectected with Lincolnshire".

About 30 naturalists met at Mablethrope, travelled to Theddlethorpe and then returned to the Book-in-Hand hotel at Mablethorpe to discuss the formation of a union.

[1] A subsequent meeting was held on 1 July 1893 at Lincoln to elect officers to organise the union.

John Cordeaux was elected as the inaugural President of the LNU and William F. Baker as its Secretary.