my blanking plate is 1/4 inch steel , a flue hole cut with the gas axe, but tidied up with a clutch ring from the inside of a tractor gearbox, perfect fit round the flue, Ive made 3 two for my houses and one for a mate.

oversized yes but the plate was laying around and had ugly bits welded on the reverse so no good for much else.

on my house I was able to knock an inspection hatch out through the outside wall, I sweep the chimney whilst stood in the garden At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

Chicken George on his second job ...

 Wales
Were the mud is thicker, and the ruts are deeper.
(And we have the water to wash it off, and more on the way..! )
Sd4 and chrome Ar*e piece, Auto box for best fun
09 Xs Gone
12 xs Gone
HSE with Leather seats and 4 years warrenty.. staying for now !

not far off the truth Im responsible for 9 chimneys - 5 on biomass boilers for poultry sheds At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

it was the TOP HAT that gave it away ....  Wales
Were the mud is thicker, and the ruts are deeper.
(And we have the water to wash it off, and more on the way..! )
Sd4 and chrome Ar*e piece, Auto box for best fun
09 Xs Gone
12 xs Gone
HSE with Leather seats and 4 years warrenty.. staying for now !

Mine has a high lintel with stove to give you an idea

Click image to enlarge

This is my setup, it's a Stovax, fits into an existing fireplace opening. Most heating is carried out by an oil fired Rayburn and the log burner is mainly used when we have power cuts (quite often), that's why there are two oil lamps on the mantle piece, they are always filled with oil and ready to go!

 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Many thanks for everyone's help and advice. Muddy wheels fireplace has convinced me to open it up. Ours is of a similar height although not quite as nice! The wooden lintel is supporting the bedroom fireplace stack so raising it would be a nightmare. I've got used to it now but a little higher would look better.