Part two of The Beauty of Maps, aired on BBC4 last night, tackled the history of London through its most notable post-1666 maps. The three featured - William Morgan's map of 1682, John Rocque's of 1746 and Stephen Walter's 2008 effort - will all be included in the Magnificent Maps exhibition, so if you want to gaze at them for hours, be my (and the British Library's) guest!

What the programme did so skilfully was to weave the sub-plots of each map into their appearance, adding voiceovers to some really quite beautiful close-ups of details. Maps can, admittedly, be quite difficult to decipher, but if the programme taught anything, it was that to trust one's eyes and to ask 'why' a map is so elegantly drawn, 'why' a map shows a cathedral that had not yet been built, can allow for a clearer understanding of the minds and mentalities of people .

As with Monday night's programme, we had an array of speakers including Laurence Worms and Tim Bryars, two of the most knowledgeable people I know.

Incidentally, you may have noticed the footage of myself and Peter arranging Rocque's multi-sheet map of London on a table. (The whole process was speeded up on film, in fact a bit of Benny Hill-esque music wouldn't have been out of place). The assembling of the sheets wasn't as straightforward as we would have liked - I found out later that the director had rearranged the sheets in the wrong order, so that it would take us more time to complete. Watch again and, at one point, we look rather confused.

Great stuff - world domination by maps is proceeding according to plan. Look out tonight for part three on the golden age of cartography, Dutch 17th-century maps. Watch especially as we take the BIGGEST atlas in the world out of its case, and then put it back again.