Around Feb/March I cleaned out our garden pond. While removing the excess mud from the bottom I disturbed 2 frogs. They are about 4/5 inches long while in the sitting position. Since then, another frog has joined them. They stay around the pond and are not frightened of us. This is the first year we have noticed frogs here but we were given some frogspawn last year so I presume they are the offspring from that. So why haven't we seen any frogspawn? I'm sure they are old enough to produce.

How are you at frog-sexing, Jenny? They could be all male or all female . It could even be a froggy gay bar you have there and the new one has just cruised by.

“They are about 4/5 inches long”

This makes me think that you might have toads and not frogs. Frogs grow to 3 inches while toads are much larger, 4 inches. A good way to tell them apart is by the skin. Frogs have smooth skin while toads have rough warty looking skin. Another way to distinguish the two is that frogs always hop or leap. Toads tend to crawl along or hop in a sluggish manner.

Male toads reach sexual maturity at 3 years of age and females at 4.

Frogs reach sexual maturity in about 2 to 3 yrs. Spawning begins depending upon the area and temperature as early as December to May, sometimes June. Both frogs and toads have a high mortality rate. Approximately 5 out of every batch of eggs laid reach to maturity.

I would say they are definitely frogs. They have smooth greeny/brown skin and they hop. The biggest one is a good 4 inches long whilst sitting.
Fred, you could be right there!