London (Agencies): Prince William's fiancee Kate Middleton has reportedly chosen the British Queen's youngest granddaughter as one of her bridesmaids.

Lady Louise Windsor, the seven-year-old daughter of Prince Edward and his wife Sophie, has been asked to accompany 29-year-old Kate down the aisle as she marries the 28-year-old Prince on April 29, the 'Daily Express' reported.

Louise was born with a rare condition, exotropia, which causes the eyes to point outwards. Her parents have so far shielded her from being snapped too much, but are said to have realised that she'll have to get used to a public life.

"Louise is thrilled to be chosen. She is absolutely cock-a-hoop and can't stop chattering about it. She'll look absolutely radiant on the day. Her mother is so proud," a Buckingham Palace source was quoted as saying.

Another insider said: "Sophie has been very helpful to Kate, advising her on all the dos and don'ts of royal life. She has been a real ally. Sophie and Edward are both really pleased to see how happy this has made Lady Louise.

"She really is the loveliest, kindest, little thing. They know she is going to have to get used to being in the limelight. She is so, so excited and they are all going to look terribly sweet walking down the aisle."

It is believed that Louise will be joined as bridesmaid by Viscount Linley's daughter Margarita, eight, and three-year-old Grace Van Cutsem, the daughter of William's friends, Rose Astor and Hugh Van Cutsem. Kate's sister Pippa, 26, is expected to be maid of honour.

Royal protocol dictates there is a "supporter" rather than a best man, and Prince Harry, is tipped to suit the role.

A source said: "It might be a global event but William and Kate see this as a proper family affair. They don't want to offend anyone and don't want to leave anyone out."