The answer is the colour BLUE!
 
(Reasons are given in brackets).
 

Which Austrian beer was first brewed and sold to the public by the Knabl family in 1800?

Puntigamer (comes in blue can)

 

Which English football team used to play at Maine Road, until they took over the stadium used for the commonwealth games in the city in 2002?

Manchester City (team colours are light blue / nickname “The Blues”)

 

Of which Austrian political party has Heinz-Christian Strache been the chairman since 23rd April 2005?

FPÖ (party colour is blue)

 

What precious stone is the single-crystal form of aluminium oxide (Al2 O3)?

Sapphire

 

What theatrical organization was founded by Phil Stanton, Chris Wink, and Matt Goldman in 1988 and now tours the world?

Blue Man Group (BMG)

 

What team won the 2007/08 super bowl 17-14 against the New England Patriots?

New York Giants (play in blue)

 

Sir Robert Peel, Benjamin Disraeli, Neville Chamberlain and Edward Heath are all linked by what British organisation?

Conservative Party / Tories (represented by the colour blue)

 

In computing, what does a hex-triplet represent?

Colours

 

What British TV service started life in 1982 as the pirate television SATV before being taken over by News Corp later that same year?

Sky TV (the sky is blue!)

 

What is the connection?

Blue

(c) the quizmaster and his friends