So murderously cold was it when the poet William Wordsworth toured Germany in 1799 that a fly froze on his heating stove. His sister Dorothy had her love to keep her warm. The fly - she wrote in her journal - had "no brother, no mate, while I can draw warmth from the cheek of my love".
This however was no comfort to the impoverished poet, who grew to suspect that Dorothy harboured more than sisterly feelings for him. According to a sensational new biography, this winter of hardship led to a secret crisis in Wordsworth's life.
It not only provoked him to "normalise his sexual relations with Dorothy". It taught him that he "somehow had to keep body and soul together". It drove the unworldly bard of daffodils and lakeland into acting as a paid spy and message-carrier abroad for the British secret service.
These charges are made in a forthcoming 1,000-page study by an acknowledged authority on the poet, Kenneth Johnston, professor of English at Indiana University. His book, due out on July 6th, will be the centrepiece of a London conference of British and American academic specialists on romantic poetry. Prof Johnston's charges are based on the discovery of an entry recording a large payment to "Mr Wordsworth" in the journal of the Duke of Portland, chief of the Home Office's obsessively watchful secret intelligence department in the years immediately after the French Revolution.
Listed before and after the poet's name in the entry are payments to two other men who, according to Prof Johnston's research in period documents, were key figures in the British spy web into which the writer was allegedly recruited.
The first man is Sir James Craufurd, British charge d'affaires in Hamburg during Wordsworth's stay there. Craufurd is on record as director of a secret Foreign Office monitoring operation in the city; Hamburg was then seething with British and Irish dissidents eager to export the French Revolution to Britain.
The second is Richard Ford, a magistrate high in the Home Office secret service - an agent who two years earlier had been involved in a bizarre surveillance of the poet. This was when Wordsworth and his fellow-poet Samuel Coleridge were suspected - during a Somerset walking tour - of spying out potential routes for a French invasion. The agent sent to watch them reported back that they were merely "a mischievous gang of dissident Englishmen".
The £92 12s paid under the poet's surname "looks like a payment-of-expenses claim" for "some kind of errand or messenger service for the Foreign Office". The sum would have almost covered Wordsworth's spending on the German tour. It also came close to the £100 a year he had said he needed to achieve literary independence.