He then moved on to Blackburn Rovers where he played 110 League and Cup games in a three-year stay at Ewood Park. Finally he finished his League career with Blackpool where his opportunities were very severely limited due to the presence of, initially, Harry Thomson, a former team-mate of his at Burnley, Neil Ramsbottom, Alan Taylor and, latterly, the emerging John Burridge.
Blacklaw was born in Aberdeen on 2 September 1937 and became a Scottish Schoolboy international before joining Burnley as a junior. He signed for the Turf Moor club as a professional in October 1954 and while with the club was an FA Cup runner-up, won a League championship medal, when he only missed one game in the 1959/60 season, and played in the European Cup. He also won two Scottish Under-23 caps and three full Scottish international caps.
He joined Blackburn Rovers for a fee of £15,000 in July 1967 and after three seasons with the club Blackpool signed him on a free transfer on 19 June 1970. Blackpool had just returned to the First Division and had 'Sir' Harry Thomson as the number one goalkeeper and when Blacklaw signed it was made clear that he was there "to provide cover in goal".
He played his first game for Blackpool in a pre-season friendly game against Port Vale on 1 August 1970 when the game was drawn 2-2 and he made a second pre-season friendly appearance against Northwich Victoria on 7 August 1970 when Blackpool surprisingly lost 2-0.
He made his first official appearance for Blackpool in the opening game of the 1970/71 Central League season, playing against Everton reserves on 15 August 1970 when he was unfortunate enough to concede a goal after just one minute but Blackpool went on to win 3-1 with the goals coming from a Rob Thomas penalty, Willie McGrotty and John Hughes. He went on to play the first nine Central League games of the season before Alan Taylor was restored to the reserve side goal. Thereafter he played seven further Central League games, spread out over the whole season, a season that was interrupted by an operation for a stomach hernia.
But on 17 October 1970 he made his League debut for Blackpool against Huddersfield Town because of an ankle injury to his former club-mate Harry Thomson. Blackpool took the lead after just six minutes through Tony Green and shortly afterwards "Blacklaw saved a certain equaliser". His best moment in the match came when he "moved off his line to dive at Smith's feet and block a point-blank drive from the winger after a through ball from Jim Nicholson had been left by the Blackpool defence and allowed to reach the Huddersfield forward". The game was eventually drawn 2-2 with Micky Burns scoring an 88th-minute equaliser for the Seasiders. Thomson was fit for the following game and with Alan Taylor re-established in the reserve side, Blacklaw was without a game the following week.
Having returned to Central League action against Stoke City reserves on 17 April 1971 when Blackpool lost 4-0 and appearing in the 2-1 defeat by Derby County reserves on 21 April 1971, he played what turned out to be his final game for Blackpool in the Central League side against Nottingham Forest reserves on 24 April 1971 when Blackpool were captained by Jimmy Armfield, who played at right half. After 33 minutes Blacklaw "made a desperate attempt to keep the ball out [from Collier's header] and although he got a hand to it was unable to stop it going in" and despite an equaliser from Alan Ainscow, Blackpool lost 2-1.
Blackpool decided at the end of the 1970/71 season that they had a surfeit of goalkeeping talent and granted Blacklaw a free transfer on 20 May 1971. 
However, on reflection and discussion between the two parties, the club cancelled his registration by mutual agreement on 30 June 1971. He had played one League game, 16 Central League games, two Lancashire Senior Cup ties and two pre-season friendly games for Blackpool in the 1970/71 season.
He went on to play non-league football for Great Harwood and Clitheroe before concentrating on his newsagent's shop for seven years. He later became steward at Burnley Cricket Club, was then a publican before finally working as caretaker-handyman at Nelson and Colne College.
He had just been invited to attend the 40th anniversary dinner for Blackpool's promotion in 1969/70 but his wife had contacted the organiser, John Cross, and said that he was too ill to attend and, sadly, he died after a lengthy period of illness on 28 February 2010.