How can I remove the waste pipe on my Creda 1200 washing machine?

My puppy has chewed the waste pipe on my machine, I have bought a new pipe today and thought it would be a simple job to replace it, but upon removing the small back panel and exposing the pipe connection, I realised that it is fixed very securely with a fitting that I'm not familiar with and I have no clue how to go about getting it off.

I normally do any household repairs myself and don't really know anyone who could have a go for me and can't really afford a plumber, if anyone can offer any advice I would be grateful.