As Series 4 of definitive spy-fi The Avengers hit UK audiences in 1965, there were some major changes, the first being the introduction of Diana Rigg as Emma Peel, replacing former sidekick to John Steed (Patrick Macnee), Dr Cathy Gale (Honor Blackman). The name Emma Peel derived from producers wanting to create a character with 'man appeal' ('M' appeal, geddit?), and formed part of a new, 'sexier' direction.

More than 80 actresses auditioned for the role before Rigg was discovered.  Her screen test with Macnee showed the two immediately worked well together, and a new era in Avengers history began. It was also this series, the last to be filmed in black and white, which was sold to US television for a then un-heard of sum of $2 million.  This made it one of the first British series to be aired on prime-time American Television.

A new direction, and a new surge of money meant a new look for the series, moving from studio-bound sets to location shots and a shift to shooting on 35mm film.  This series notably became more light-hearted due to Macnee and Peel's new relationship.  A more jovial script also opened doors for more humour and to poke fun at its American counterparts such as Mission...Highly Improbable and The Winged Avenger.

The increased popularity of spy-fi meant many episodes were characterised by a futuristic, science fiction bent than in previous series, including mad scientists and their creations leaving havoc in their wake, giant carnivorous plants, and invisible foes. This enabled an erotic undercurrent, also demonstrated in Emma Peel's costumes, which including fashions that were considered avant-garde for the time: bold accents and high-contrast geometric patterns emphasising her youthful contemporary personality, and representing modern sixties England. Fetishism is even hinted at in some episodes including, A Touch of Brimstone, where Rigg was dressed as a dominatrix to become the Queen of Sin'. This was one of five episodes from Series 4 that were not initially broadcast in the US by ABC due to censors deeming it too racy for American audiences.

The Avengers: The Complete Series 4 is coming to UK DVD on 5th July 2010 from Optimum Home Entertainment as a 7-disc set featuring the first full restoration of all episodes and over six hours of bonus features, all at the RRP of £59.99. Listed extra features are (deep breath):

• Exclusive audio commentary for The Town of No Return with director Roy Ward Baker and scriptwriter/producer Brian Clemens;
• Exclusive audio commentary for The Master Minds with scriptwriter Robert Banks Stewart;
• Exclusive audio commentary on Dial A Deadly Number with scriptwriter Roger Marshall;
• Exclusive audio commentary on The Hour That Never Was with director Gerry O'Hara;
• Exclusive audio commentary on The House That Jack Built with director Don Leaver;
• The Series of No Return - Exclusive audio interview with Elizabeth Shepherd;
• Armchair Theatre – The Hothouse (starring Diana Rigg);
• USA Chessboard opening sequence;
• Strange Case of the Missing Corpse promotional trailer;
• Alternative end tag from Death At Bargain Prices;
• Episode reconstructions for series 1 scripts Kill The King and Dead of Winter;
• Colourised test footage from Death At Bargain Prices and A Touch of Brimstone;
• Reconstructed 'The Avengers are back' John Stamp trailer;
• Alternative UK opening and closing credits;
• Alternative UK animated bumpers;
• UK animated bumper;
• Variant opening title credits for The Gravediggers;
• French opening credits;
• German opening credits;
• ITN Newsreel footage;
• Stills galleries;
• PDF material (scripts, TV Times, ABC Production paperwork).