I would suggest you post your question on the Ponds forum at the link below. It is more active than this forum and those folks can tell you what you need to do.

Here is a link that might be useful: Ponds & Aquatic Plants

I have two ponds and many frogs. Your frogs need water. They will probably return or new ones will find your newly filled pond when it's ready. They will not return until they have a place to live. They spend a good portion of their time underwater including winter. Toads on the other hand are land dwelling creatures. If you like frogs get that pond refilled or put in another. For now they have sought out a new home.

Paul, How big is your pond, and how big the garden? Indeed, frogs are to be cherished, so do what you can to fill the pond.

I live on a mostly shallow pond of 9 acres, with only a few places where cattails grow. But that seems to be where the frogs congregate. The blue heron comes to hunt them, and the subdivision cut down most of the cattails, so our frog population has shrunk.

I am familiar with Devon and its mild maritime climate.
You can make a frog friendly pond and skip the fish. If the water is stale, buy a small aerator pump. Inexpensive to buy and operate. There are lots of lovely pond plants that would make your yard beautiful. Those frogs will hop right in and reproduce.

Good luck to you Paul. Pondy