Study the skies carefully and you may spot two spectacular birds successfully reintroduced to England.

Many are mistaken believing the beautiful Red Kite and huge White-tailed Eagle to be so rare they are confined to small and remote areas of the country. I have seen several fork-tailed Red Kites sailing over Sidcup this year while a White-tailed Eagle, also known as the Sea Eagle, was satellite-tracked over central London and down the Thames via Dartford Marshes on its way to the Sussex coast.

Alas the eagle flew so high it remained invisible to most but there is every chance of future sightings locally. This enormous fish-eating bird, known as “the flying barn door”, went extinct in Britain in the early 20th century due to pollution and persecution but individuals from a recent Isle of Wight release spread their wings to investigate southern England.

Red Kite numbers are also increasing in England and Scotland after being limited to a handful in a small part of Wales in the 1960’s. A key figure involved in re-introductions of both species is Roy Dennis, a former Royal Society for the Protection of Birds employee, now a wildlife consultant.

Dennis battled for years against red tape, sceptical scientists and fearful farmers in his efforts to win support for re-introductions. Scientists claimed his projects wouldn’t work, politicians sat on their hands and farmers tut-tutted but he never gave up.

Apart from the birds mentioned above, Dennis helped introduce Ospreys at Rutland Water, increased the Scottish Osprey population and worked on an Irish Golden Eagle project before turning to Red Squirrels then planning Beaver transfers from Norway to Sandwich, Kent, for experimental trials.

Now the enterprising Dennis, who received an MBE for services to nature conservation,  has written about his life challenging beauracracy for permits to restore “lost” wildlife. His excellent book “Restoring the Wild” charts successes and failures in this 60-year struggle and peers into the future.

Dennis foresees more Beaver introductions, a limited Lynx project and discusses the futures of Elk, Great Bustards and Eagle Owls in the UK but is less confident about Brown Bears and Wolves ever being released.

Restoring the Wild by Roy Dennis is published by William Collins price £18.99.