The fly-past will take place at 20.45 EET over Freedom Square in Tallinn, with the choppers flying in a northwesterly direction, EDF spokespersons said on Tuesday.

''Supporting Estonia and its NATO allies is a challenge that offers a great opportunities for all in Estonia to see Army Air Corps squadron officers and personnel," said Maj David Lambert, commander of 663 Squadron, AAC.

The AgustaWestland Apache attack helicopters, and the AgustaWestland AW159 Wildcat utility helicopters, arrived last weekend, according to an EDF press release.

The main task of the AAC helicopters in Estonia is to support and augment the UK-led NATO Enhanced Forward Presence (eFP) Battle Group serving at Tapa base. The helicopters will provide fire support for the annual exercise Spring Storm organised by the EDF and NATO and due to start on 29 April.

"Whenever the call comes from NATO, the UK has always been ready to reach into its full spectrum of capabilities and offer its support. That's why we're bolstering training in Estonia, by deploying some of the world's most advanced helicopters to the country," said UK defence secretary Gavin Williamson (Conservative), as reported by spokespersons in January, when the deployment was announced.

The eFP sees troops from the UK rotate in and out at various intervals, and currently forms its basis around the Kings' Royal Hussars cavalry regiment, which operates Challenger 2 Main Battle Tanks. Other nationalities whose forces are currently serving in the Battle Group include Belgium and Denmark.

The Veterans' Rock Concert honours Estonian veterans' day, held on 23 April each year. Noted Estonian acts taking part include Tanel Padar, and Elephants from Neptune.

23 April is also a national day both in Estonia, where it marks the anniversary of the 1343 Jüriöö (''George's night'') uprising in northwestern Estonia, and in (part of) the UK, since St George is the patron saint of England.