Pamg, Moon grower, Noseypotter....such excellent answers. I feel much more comfortable getting on with the pond...Thank you all so much

You are welcome

hope your pond gives you pleasure-- we've a coot nesting at the moment but dread the heron coming!

Oh wow Pam a coot - I think our cats would deter one here. Yes I can imagine the heron is rather a challenge.

they are lovely Mg and the parents are around all year but I must say that they're not very bright-- if you come on them unawares they make straight for the hedge-bottoms sticking out- and the poor babies scatter to the four winds
they do seem to rear some chicks though tiny black babies that bob around like corks :0)