With over seven years of television adventures under his belt, Tom Baker is still the longest reigning Doctor to date – and this weekend we're happy to be bringing you some special offers on his audio adventures.

Both Series 1 and Series 2 of Doctor Who: The Fourth Doctor Adventures are on special offer, with each release available for just £5 each on CD or £2.99 to download. Join the Doctor and Leela (Louise Jameson) as they return to Space Station Nerva, endure the Wrath of the Iceni, cross paths with the Master or join UNIT in fighting off the latest Kraal invasion.

Or revisit the Doctor's voyages with Romana (Mary Tamm) for adventures with Jago & Litefoot (Christopher Benjamin and Trevor Baxter) and a voyage under the sea – before a climatic clash with the scheming Cuthbert (David Warner) and his new corporate allies – the Daleks!

You can pick up both series today in a series of special bundles – Series 1 is just £20 on CD or £12 on download, with Series 2 just £25 on CD or £15 to download. Both Series can be picked up together with Doctor Who - The Lost Stories: The Fourth Doctor Boxed Set for just £60 on CD or £45 to download.

We've also discounted two amazing Fourth Doctor box-sets. Doctor Who – The Lost Stories: The Fourth Doctor Box Set comes down this weekend only to an unbelievable £25 on CD or Download, and Doctor Who – Phillip Hinchcliffe Presents... Volume 1 is £45 on CD or £40 to download. Both sets can be bought together in a bundle for a money-saving £65 on CD or £60 to download.

You can also pick up everything on offer for just £100 on CD or £80 to download – and all Bundles come with free UK delivery and reduced shipping for overseas customers. As ever at Big Finish, all CD purchases in this promotion unlock instant access to the Download so you can be listening within minutes of buying the stories!

These special offers must end at Noon, Monday 19th of October (UK time) – so order now before time runs out!

The Fourth Doctor will return in January 2016 in Doctor Who: Wave of Destruction, the first title of Series 5 of the Fourth Doctor Adventures. You can pre-order this new season, alongside Series 6 today from the Big Finish website.

As traditional on a Friday we've released the latest free podcast and download of Toby Hadoke's Who's Round, and join us tomorrow for the next special offer related to the broadcast of the latest Doctor Who episode on television!