Contact this Vet.
http://www.poultryhealthcentre.com/mainpages/practice.htm
He will tell you how to get a pigeon down to him.
Can be contacted by letter at:- 77 The Down, Trowbridge, Wiltshire, BA14 7NG
by email:- dgp@poultryhealthcentre.com
by mobile and text:- 07811 155387