You will be given a definition of a task first, then some input of the task.
In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: The original catalyst for development was the ill-fated vanity project by Lord Kensington (died 1852) which consisted of the two-mile conversion of the insanitary Counter's Creek into the Kensington Canal (1826 onwards), followed by its eventual replacement first by "Mr Punch's railway", opened in 1844 and next, by the Metropolitan District Railway in 186569, which eventually became London Underground's District Line and was joined after 1907 by the Piccadilly line. Meanwhile, the congestion apparent in London and Middlesex for burials at the start of the century was causing public concern not least on health grounds. In 1837 a decision was made to lay out a new burial ground on the edge of Earl's Court in an outlying area of Brompton. The moving spirit behind the project was the engineer, Stephen Geary. It was necessary to form a company in order to get parliamentary permission to raise capital for the proposal. Securing the land some 40 acres from local landowner, Lord Kensington and the Equitable Gas Light Company, as well as raising the money proved an extended challenge. After two years the cemetery was duly established by Act of Parliament and laid out in 1839, it opened in 1840, originally as the West of London and Westminster Cemetery. It was consecrated by Charles James Blomfield, Bishop of London in June 1840, and is now one of Britain's oldest and most distinguished garden cemeteries, served by the adjacent West Brompton station.
Link Information: the GNP&BR was formally opened on 15 December 1906 Question: How many months after the Piccadily line was created did it join with the London Underground's District line?
Output:
Answer: 1