sentences:  There is speculation that a section called The Narrows was lined with concrete and faced with bricks to prevent leakage into a large neighbouring property, Aston Clinton House, but this is unconfirmed.The company tried using asphalt to line the canal in 1857, but that failed after 13 years, due in part to inexperience in the use of the material.In 1897, which was drier than usual, the Grand Union company decided that the arm was leaking more water than it was supplying, and stop planks were used to block off the arm at Little Tring.