I think it MAY be earlier than 1951. My mother was married (in Australia) in 1942 and her bridesmaids definitely wore veils. In my mother's case the bridesmaid veils were shorter than the bride's and their dresses were coloured, which obviously can't be sure of here. It looks as though the two 'outer' girls' veils may be shorter than the girl in the centre.
Remember, whether 1951 or earlier, rationing was still in and clothing coupons hard to come by, so dresses for a wedding party were often a bit 'make-do', often acquired through borrowing. My mother's wedding dress was worn by three brides and the bridesmaids' dresses used again for another wedding.
Even the Queen was not exempt in 1947 - however not many brides had her gorgeous embroidery and the use of a diamond tiara.
(From Wikipedia)
On account of the austerity measures following the war, Princess Elizabeth had to use clothing ration coupons to pay for her dress. The government allowed her 200 extra ration coupons. She was given hundreds of clothing coupons by brides-to-be from all parts of the country to help her pay for her dress. She had to return the coupon gifts as it was illegal for her to use them though.
I think that this is one wedding couple and two sets of attendants.
Judith