Despite its name, the school accepts boys of all abilities, although approximately a third are selected for academic or musical aptitude, and brothers of existing pupils are also guaranteed places.

[3][4] The £52 a year was augmented with bequests, producing a revenue of £178, but the rent-charges were fixed and lost their value through inflation.

On 23 February 1912, the boys assembled outside the Derby road buildings and walked to the new site, which was formally opened by the Earl of Clarendon on 20 March 1912.

In 1924, Rugby union was introduced in the boys' school and took over from football as the main winter sport.

They became grant-maintained schools in 1990, controlled by their own governing bodies, independent of the county council, and funded directly by the Department for Education, and in 1995 introduced partial selection.

The selective proportion of their intake has been reduced since 1995, and currently stands at 25% academic and 10% musical aptitude.

Their catchment area for selective admission reaches out about 5 miles, including some northern parts of the London boroughs of Harrow and Hillingdon.

[9] Every year there is a Founder's Day service to commemorate the charitable foundations and to celebrate Dame Elizabeth Fuller's commitment and dedication to the school.

In 2016 The Independent Newspaper Published a table listing Watford Grammar School for Boys as the 7th Best Comprehensive or Partially Selective in the United Kingdom.

The 120-metre (390 ft) long neo-Georgian main block and the adjacent Master's House are Grade II listed buildings.

[14] In recent years the school has built a gym, a music block (also partly owned by Hertfordshire School of Music) and a Sixth Form centre with a food technology lab, financed through fundraising and the sale of land on the northern edge of the grounds for residential development.

[16] The building was completed in December 2007 at the cost of £5 million, and has approximately 2,000 square metres (22,000 sq ft) of space spread out over four floors.

Funding was providing by national and local government and parental donations supported the fittings and fixtures of the building.

This is currently achieved by raising funds for selected school projects and also by giving Old Boys opportunities to stay in touch with each other and with the school through events including the annual OFA Dinner, through newsletters and also through the very strong cricket and golf sports societies.