My first convention was SEACON 75, the 1975 UK National SF convention, held that year in Coventry. Among the many items on the programme was the Fancy Dress which - as that name implies - was largely an excuse for attendees both pro and fan to dress up more as a bit of fun than anything more serious. (It was either that year or the one after that editor Don Wollheim entered as author Isaac Asimov and female fan Lee Montgomerie as author Christopher Priest.) In the US they had the convention Masquerade and a group of fans had emerged who took costuming very seriously and whose elaborate costumes involved the investment of a lot of time, money, and effort. It would be a while longer before that level of investment showed up at UK conventions, imported at least in part by those who had started out in Star Trek fandom. When it did there was initially a degree of animosity towards these costumers from more traditional fans of SF literature since reporters inevitably focussed on those in costume to the extent that as far as those getting their view of SF fandom from TV and newspaper reports were concerned the costumers were the face of SF fandom, and it was not a face those who wanted SF to be accorded some respect thought helped in that quest. Over time, as press coverage improved and conventions were accorded more respect, that resentment faded, but for a while it was very real.

The first SF convention was held in Leeds, England in January 1937 and was a very serious and sober affair. The 14 or so attendees were all male and the closest they came to costuming was that one of them - Ted Carnell - didn't wear a tie. The first Worldcon was held in New York in July 1939 and, so far as I'm aware, was the first occasion on which someone wore a costume at an SF convention. That person was Forrest J Ackerman, who was one of three Los Angeles fans - the others being Morojo and a young Ray Bradbury - who attended. And as it happens photos of that costume have survived. (Addendum: Apparently Morojo's dress was also a costume, the pair representing people of the future, and she made both of them.)

Forry Ackerman and Myrtle 'Morojo' Douglas at NYcon, 1939 - (photo from Ted Carnell collection)

This inspired those running the 1940 Worldcon to stage the first Masquerade to be held at an SF convention. I tell the stories of both this and of Morojo here:

• Myrtle 'Morojo' Douglas: Mother of Cosplay
• The First Masquerade and the Birth of Cosplay

I don't have too many costuming photos from the 1940s, but here's one from the 1949 Worldcon. There was no Masquerade at the convention, Lois Miles being a model who had been brought along by Dave Kyle as part of a PR attempt. (For other photos from the 1949 Worldcon see here):

Lois Miles as "Miss Science Fiction" - (Ted Carnell collection)

Earl Kemp kindly supplied me with a bunch of photos from his albums from 1950s Worldcons. Here are some from the 1952 Worldcon. As can be seen from the label, the Masquerade was clearly part of the convention by this point, having presumably been added at some point between 1949 and 1952. (Photos by Karen Anderson):

Sisters of the Galactic Order of Serena

The earliest costuming at UK conventions appears to have been at CORONCON, the 1953 UK National Convention. This was not for a Fancy Dress event but as part of a 'ballet', and involved several male fans donning drag and Dorothy Rattigan in the costume she's pictured in below, the first ever to be worn at a UK con:

Dorothy (Jacobs) Rattigan (Vince Clarke collection)

Fred Brown, Ted Tubb, Ron Buckmaster, Charlie Duncombe. (Vince Clarke collection)

• Dramatic Presentations by Fans at UK Conventions from 1950

The 1954 UK National Convention, SUPERMANCON, was held in Manchester. The Liverpool Group had decided beforehand to make their party a Fancy Dress party and a few had prepared costumes. Others joined in, primarily through the medium of hats. All photos Eric Bentcliffe. collection:

Fan artist Brian Lewis (*not* the future pro artist)

John Roles, Pete Taylor, John Brunner

John Roles with Lensman tie

Ina Shorrock, Terry Jeeves, Pat Doolan, Eric Bentcliffe - Pat and Ina are dressed as 'Bergey Girls'

The 1954 Worldcon, and the quality of the costuming has improved noticeably since the 1952 Worldcon. (Earl Kemp collection. Photos by Karen Anderson except where noted):

unknowns	unknown, Bill Eisenlord
Karen Anderson as PLANET STORIES cover heroine, unknown (photographer unknown)
Clockwise: Willy Ley, unknown, unknown, Olga Ley	Jeanne & EE 'Doc' Smith at rear, unknown in costume

CYTRICON was the 1955 UK National Convention, the first of a run of four CYTICONs that would be run in the town of Kettering over the next four years. The Liverpool Group once again hosted a Fancy Dress party and had prepared costumes accordingly (they were the only ones in costume this time). All photos Norman Shorrock collection:

Norman & Ina Shorrock

Full view of Ina's valkyrie costume

Harrison, Daphne Buckmaster, Stan Nuttall, John Roles

Costume colours

The Liverpool Group must have enjoyed wearing costumes at CYTRICON because the following year, at CYTRICON II, they really went to town. According to notes, Renee MacKay was Cleopatra, Stan Nuttall was Mark Fanthony; Ina Shorrock was a Krishnan woman (in green paint); Dave Newman as Attila the Fan; Don MacKay was Erik the Bent, and in the BEM suit was Eric Jones:

BEM, cartoonist Arthur 'ATom' Thomson

Rene MacKay, John Roles

Ina Shorrock, Rene MacKay, Dave Newman, Stan Nuttall

Don MacKay, Lil MacKay, Pat Doolan, John Roles

In 1957 the Worldcon came to London for the first time. Here's a link to a gallery of Masquerade photos on the part of this site devoted to that convention:

• 1957 Worldcon Masquerade

• Tolkien at the 1958 Worldcon