7 mid 19th Century German physicists

1. Max Planck
2. Woldemar Voigt
3. Karl Ferdinand Braun
4. Leo Graetz
5. Heinrich Rudolf Hertz
6. Heinrich Kayser
7. Ernst Karl Abbe

7 operas by Pyotr Tchaikovsky

1. The Enchantress
2. The Maid of Orleans
3. The Queen of Spades
4. The Oprichnik
5. Vakula the Smith
6. Cherevichki
7. The Voyevoda

7 cars participating in this year's Mille Miglia

1. BUGATTI Type 35 1925
2. ASTON MARTIN Le Mans 1933
3. BRISTOL 400 1948
4. FERRARI 340 America 1951
5. MASERATI A6G/54 1955
6. ABARTH 750 GT Zagato 1957
7. AC Ace 1956

7 Buckingham candidates I won't be voting for

1. Nigel Farage (UKIP)
2. Lynne Mozar (BNP)
3. Simon Strutt (Cut the Deficit Party)
4. Anthony Watts (Independant)
5. Colin Dale (Monster Raving Loony Party)
6. Patrick Phillips (Independant)
7. David Hews (Christian Party)

7 species of hummingbird

1. Bee Hummingbird
2. Magnificent Hummingbird
3. Green Violet-ear Hummingbird
4. Rufous Hummingbird
5. Short-tailed Emerald Hummingbird
6. Ruby-throated Hummingbird
7. Costa's Hummingbird

7 types of oil platform

1. Fixed Platform
2. Compliant tower
3. Jack-up platform
4. Tension-leg platform
5. Spar platform
6. Drillship
7. Semi-submersible platform

Formula classes of Formula racing

1. Formula 1
2. Formula First
3. Formula Libre
4. Formula Mondial
5. Formula Pacific
6. Formula Nippon
7. Formula Junior