This week marks the sesquicentenary – or 150th birthday - of the tube.

Yes, even though it sometimes seems like the engineering of the Northern Line predates the battle of Hastings, or that bewildered travellers have been trying to circumnavigate the Circle Line since the time of Columbus, the tube is actually only 15 decades old.

The first journey on what we now know of as London Underground took place on January 9 1863, between Paddington and Farringdon Street on the Metropolitan Line. Historians believe that was the last time there was good service on all London Underground lines.

Tube enthusiasts might find plenty to adore about London's transport network. Personally, I'm not always a fan, but I do love the vintage posters from the days when taking the tube was a leisure activity, rather than an exercise in armpit-avoidance and diagonal newspaper reading.

For two wonderful examples of the artwork, we can look no further than the posters of Harry Blacker, the Jewish cartoonist known as "Nero", who also designed posters for BP and the Post Office.

The first, "Zoo nights" is from 1939, the second is from the year before and is called "AAA Championships" (Photos courtesy of London Transport Museum). Lovely.