The Jubilee issue replaced the 'unified' lilac and green issue of 1883, only the £1 has corner letters. The 1881 penny lilac was also used at this time. The 10d was issued later on 24 Feb 1890 and the 4½d on 15 Sep 1892, the £1 was issued on 28 Jan 1891. It is only coincidental that these stamps were issued at the time of the Queens Jubilee (50 years on the throne). It is also the time that Queen Victoria appeared in public after mourning the death of her husband, Albert, in 1861 (after 21 years of marriage, when she was 44). She lived in seclusion for over 25 years until her Jubilee in 1887 (when she was 70).