First attempt to deliver Ivan to the Yorkshire border (with Lincolnshire): Leeds to the Humber Bridge is about 60 miles; the bridge itself, that joins the two counties, is about a mile and a half across, and opened in 1981. Lincolnshire presumably occurs at the halfway point of the public footpath southward along the bridge.
The two-volume "Alphabetical Guide to Sexual Behaviour" seems to be an invention of Alan Plater. "Sex A - Z: An alphabetical guide to all kinds of sexual practices, preferences and proclivities", the nearest equivalent available on a contemporary global retail delivery service, only dates to 2013, long after the Beiderbecke Trilogy was completed.
Second attempt to deliver Ivan to the Yorkshire border (with Lancashire): Big Al's map shows a drop point slightly south-east of Pateley Bridge. This suggests a crossing over the River Nidd near Summerbridge, well short of the border, so doomed to failure.
Although Mr Pitt and his jazz club are Alan Plater's inventions, Frank Ricotti, topping the bill at the Village Vanguard aka Limping Whippet tonight, is very real: [from Wikipedia] Between 1984 and 1987, Ricotti wrote the soundtrack music for Yorkshire Television's The Beiderbecke Trilogy, in the style of Bix Beiderbecke. The music was performed by his band, the Frank Ricotti All Stars, and featured Kenny Baker on cornet. A soundtrack album was released in 1988.