From office sweepstakes to online bookmakers, across Europe millions of pounds are bet on the Eurovision song contest every year. But is it in any way possible to predict the winner? To the outside eye, a roll-call of recent victors could scarcely look more random: a heavy metal monster band, a bearded lady, a pair of middle-aged Danish brothers, a teenage fiddler.

Taking a closer look at the songwriting trends in recent years, however, shows that it may not be such a crapshoot after all.

The language

Owing to a change of rules in 1999, Eurovision entrants are now allowed to write in any language that they choose. A few countries stubbornly persist in sticking their mother tongue out even though there is no absolutely no discernible benefit in doing so (Olá, Portugal!) but most end up trying their hands at English in order to be at least vaguely understood by the maximum possible number of countries.

It’s worth the extra effort. Only one winning song has been sung in a language other than English since those language rules were relaxed – and that was Serbia’s 2007 entry, Molitva, by KD Lang-a-like, Marija Šerifovi.

And while Ruslana sang Wild Dances in both English and her native Ukrainian (a trick replicated this year by Romania’s Voltaj – a sketchy dad-rock group, fronted by a guy who looks like a low-rent Vegas illusionist) an overwhelming 90% of the winning entries in recent years have been performed in English.

The key

D minor was famously hailed as ‘the saddest of all keys' by Spinal Tap’s Nigel Tufnel

D minor was famously hailed as “the saddest of all keys” by Spinal Tap’s Nigel Tufnel but it’s the cause of nothing but celebration at Eurovision.

Despite having a reputation as being a happy, campy clap-a-long, since the turn of the century, audiences and juries have shown a consistent preference for songs in minor keys. D minor in particular has provided four of the last seven winners: Molitva (2007), Fairytale (2009), Satellite (2010) and Rise Like a Phoenix (2014).

The key change

Considered by many to be a quintessential part of the Eurovision experience, the data show that very few Eurovision entries actually use key changes. The last winner to use one was (again) Moltiva in 2007, and since then winners have not really bothered with them.

It’s a good job too, because they are a high-risk, low-gain strategy. A switch in pitch needs to be executed with clinical precision, otherwise – like a sleepy drunk – they will lose their footing, drop their key and then spend the rest of their evening fruitlessly scrabbling around in the dark for it.

The tempo

Only one pattern emerges from studying the tempos of winning and losing songs in Eurovision, and it is this: if speed kills, then 128 beats per minute is a multiple murderer. Four entries paced at 128bpm have come dead last since 2000, and another two paced at 127bpm have too.

The lyrics

Given that most of the songwriters in the contest are working in their second, third or (occasionally) fourth language, the difference between a successful and unsuccessful songsheet is surprisingly nuanced. For example, two winners since 2000 have sung about having something in their arms, but four losing entries have sung about having something in their hands.

Mentioning your heart is a really bad idea (nine losers have done so); mentioning your eyes is a pretty good one (as four winners found out); but, as Lena proved with Satellite in 2010, mentioning your underwear is a really good one.

Also of note – in keeping with the our preference for sad songs – lyrics which reference bad weather (thunder, lightning, raindrops, etc) have been more successful than lyrics which reference blue skies and sunshine.

Russia and Sweden feature a homophone in their lyrics, and it might be this that holds the key to the whole competition

So what does all of this tell us about this year’s contenders? Well, if last night’s semi-final is anything to go by:

1. We lost the only entry not to have any English lyrics (Finland’s Aina Mun Pitää), which means we can probably safely wave goodbye to Spain, France, Portugal and Montenegro’s chances too. Italy is a slight wild card here, as the betting markets seem to think will put in a Top Three performance, but they’re so cute they could sing in Klingon for all anyone cares.

2. Denmark and the Netherlands also crashed out with songs in major keys (C and F# respectively), which is not a good sign for the Bugsy-lite UK entry (also in C major). Or for Lithuania. Or Cyprus. Or Ireland.

3. Serbia made it through to the grand final, but paced at 128bpm, it might not fare so well come Saturday.

4. Greece also qualified last night with one of the only two songs in D minor this year (something which bodes well for the Czech Republic tomorrow).

5. Russia is best placed to buck the minor key trend (it’s in G major), but the bookies do still have them in second place to Sweden (Ab minor).

6. Interestingly, Russia and Sweden feature a homophone in their lyrics, and it might be this that holds the key to the whole competition. Because while Sweden makes reference to a “son”, Russia makes the historically fatal mistake of referring to the “sun”.

Whether that’s enough to cost them the contest though, we’ll have to wait and see …