What is this?

What is this?

Observation - What is this? - UK and Ireland. Description: i noticed this insect in my garden today just as my dog was about to pounce on it for a chew, so i saved it and would like to have it identified. can you help? to me it looks similar to a hornet but it is much much bigger

i noticed this insect in my garden today just as my dog was about to pounce on it for a chew, so i saved it and would like to have it identified. can you help? to me it looks similar to a hornet but it is much much bigger