A (not entirely serious) talk that I gave at the London Perl Mongers technical meeting in March 2018. It talks about how and why I build a web site listing the line of succession to the British throne back through history.

1. I’m A
Republican
(Honest!)

9. Not hard to
become a
Quora expert

10. Who will succeed
the Queen of
England?

11. Why does Britain
always have a
queen not a king?

12. Who would be king
if Prince Charles
dies before Queen
Elizabeth II?

13. What must Prince Charles
actually feel about his
mother pulling him from
the line of succession and
designating his son as heir
to the throne?

14. Did the Queen
assassinate
Diana, Princess of
Wales?

15. How to become
king or queen of
the UK*

16. How to become
king or queen of
the UK*
* Andfifteen other
Commonwealth Realms

17. Step 1.
Be a close relation
of the monarch

18. Step 1a.
Don’t be a woman
with a younger
brother

19. Step 2.
Don’t die before
the monarch

20. Step 3.
Don’t be
illegitimate

21. Step 4.
Don’t be a
Catholic

22. Step 4a.
Don’t marry a
Catholic

23. Recent(ish)
updates

24. Succession
to the Crown
Act (2013)

25. Step 1a.
Don’t be a woman
with a younger
brother

26. Step 1a.
Don’t be a woman
with a younger
brother

27. Step 4a.
Don’t marry a
Catholic

28. Step 4a.
Don’t marry a
Catholic

29. Updated:
* Be royal
* Be alive
* Be legitimate
* Don’t be Catholic

30. Brilliant
Idea!

31. Let’s calculate the
line of succession
on every date
back to 1701

32. How hard
can it be?

33. Family
Tree

36. That’s gets
17 people

37. More Data
Needed

38. Descendants
of George VI

39. Descendants
of George V

40. Descendants
of Edward VII

41. Descendants
of Victoria

42. (Eventually)
Descendants
of Sophia

43. Wikipedia is
your friend

44. Some
complications
...

45. Titles and
names

46. * Princess Elizabeth of York
* The Princess Elizabeth
* The Princess Elizabeth,
Duchess of Edinburgh
* Queen Elizabeth II

47. Add a titles
table

48. Exclusions

49. Excluded because
you married a
Catholic

50. Included because
you divorced a
Catholic

51. Included because the
law on being
excluded for
marrying a Catholic
changed

52. Excluded because
you became a
Catholic

53. (Children aren’t
officially Catholic
until their
confirmation)

54. Male-preference
primogeniture

55. Abolished in
2013
(Mar 27)

56. For children
born after
28 Oct 2011

57. Senna Lewis
(b 22 Jun 2010)
24th
in line

58. T ne Lewisā
(b 25 May 2012)
26th
in line
(Senna is 27th)

59. 26 March 2013
26: T ne Lewisā
27: Senna Lewis

60. 28 March 2013
26: Senna Lewis
27: T ne Lewisā

61. Dancer2
App

62. Some data
presentation
challenges

65. Find nearest
common
ancestor

66. Count
intervening
generations

68. Easy to do
A lot of data
to crunch

69. Enter
memcached

70. CHI

71. has cache => (
is => 'ro',
isa => 'CHI::Driver::Memcached',
lazy_build => 1,
);
sub _build_cache {
return CHI->new(
driver => 'Memcached',
namespace => 'succession',
servers => [ 'localhost:11211' ],
debug => 0,
compress_threshold => 10_000,
);
}

72. sub get_relationship_between_people {
my $self = shift;
my ($person1, $person2) = @_;
my $relationship = $self->cache->compute(
'rel|' . $person1->id . '|'
. $person2->id,
undef,
sub {
return
$person1->relationship_with($person2);
}
);
return $relationship;
}

73. Didn’t
work

75. Two lessons
learned

76. Always use a
model layer

81. Batch
job

82. Calculate
succession on
every date

83. Note the
dates when it
changes

84. Dates in
URLs

85. https://lineofsuccession.co.uk/
https://lineofsuccession.co.uk/2018-01-01
https://lineofsuccession.co.uk/2016-01-01

86. All the same
content

87. Duplicate
content is
bad

88. Canonical
Tag

89. <link rel="canonical"
href="https://lineofsuccession.co.uk/" />
<link rel="canonical"
href="https://lineofsuccession.co.uk/2014-
01-17" />
<link rel="canonical"
href="https://lineofsuccession.co.uk/1901-
01-22" />

90. More
SEO

91. Structured
data

92. <li itemscope
itemtype="http://schema.org/Person">
<span itemprop="name">The Prince
Charles, Prince of Wales</span>
<br><span class="small">Age 69
(born <a title="Line of Succession on
14&nbsp;November&nbsp;1948"
href="/1948-11-14">
14&nbsp;November&nbsp;1948
</a>),
<br>Son of the sovereign
</span></li>

93. <li itemscope
itemtype="http://schema.org/Person">
<span itemprop="name">The Prince
Charles, Prince of Wales</span>
<br><span class="small">Age 69
(born <a title="Line of Succession on
14&nbsp;November&nbsp;1948"
href="/1948-11-14">
14&nbsp;November&nbsp;1948
</a>),
<br>Son of the sovereign
</span></li>

94. Google likes
structured
data

95. Todo

96. Moar
data

97. Moar
views

98. Moar
marketing

99. https://lineofsuccession.co.uk/
https://github.com/davorg/succession
@linesuccession
@davorg

100. Vive la
révolution!