1 Negotiates airports with ease
2 Never lets a door slam in someone's face
3 Can train a dog and a rose
4 Is aware that facial hair is temporary, but a tattoo is permanent
5 Knows when not to say anything
6 Wears his learning lightly
7 Possesses at least one well-made dark suit, one tweed suit, and a dinner jacket
8 Avoids lilac socks and polishes his shoes
9 Turns his mobile phone to silent at dinner
10 Carries house guests' luggage to their rooms
11 Tips staff in a private house and a gamekeeper
12 Says his name when being introduced
13 Breaks a relationship face to face
14 Is unafraid to speak the truth
15 Knows when to clap
16 Arrives at a meeting five minutes before the agreed time
17 Is good with waiters
18 Has two tricks to entertain children
19 Can undo a bra with one hand
20 Sings lustily in church
21 Is not vegetarian
22 Can sail a boat and ride a horse
23 Knows the difference between Glenfiddich and Glenda Jackson
24 Never kisses and tells
25 Cooks an omelette to die for
26 Can prepare a one-match bonfire
27 Seeks out his hostess at a party
28 Knows when to use an emoji
29 Would never own a Chihuahua
30 Has read Pride and Prejudice
31 Can tie his own bow tie
32 Would not go to Puerto Rico
33 Knows the difference between a rook and a crow
34 Sandals? No. Never
35 Wears a rose, not a carnation
36 Swats flies and rescues spiders
37 Demonstrates that making love is neither a race nor a competition
38 Never blow dries his hair
39 Knows that there is always an exception to a rule
Titled 'How to be a Modern Gentleman', should be titled 'How to be a Proper English Gentleman' since most of us on this side of the pond don't know what some of those terms mean
Also 19 should be 'Can undo a bra with his teeth'