Pietersen's double debut double

Kevin Pietersen scored two half-centuries on his Test debut - how unusual is this? asked Jeremy Gilling from Australia (and several others)

The feat is relatively uncommon - Kevin Pietersen was the 31st man to make two scores of 50 or more on his debut Test, at Lord's last week. The most recent before him was his team-mate Andrew Strauss, against New Zealand at Lord's last year. Six others have achieved the feat for England: KS Ranjitsinhji in 1896, George Gunn in 1907-08, Paul Gibb in 1938-39, Cyril Poole in 1951-52, Peter Richardson in 1956, and Tony Greig in 1972. The only other man apart from Strauss and Pietersen to do it at Lord's was the New Zealander Merv Wallace, in 1937.

Pietersen also top-scored in both innings on debut - how uncommon is that? asked Raushan Ranjan, among others

This feat is indeed more unusual than the first one - Kevin Pietersen is the 14th man to achieve this in a Test, and the fourth for England after Edmund Tylecote in 1882-83, George Gunn (1907-08) and Tony Greig in 1972. The others are the Australians Harry Moses (1886-87) and Reggie Duff (1901-02), Bernard Tancred of South Africa (with twin scores of 29 in 1888-89), the Indians Lala Amarnath and Dilawar Hussain (both in 1933-34, India's first home series), Lawrence Rowe of West Indies (1971-72), Pakistan's Taslim Arif (1979-80) and Yasir Hameed (2003-04), Lee Germon of New Zealand (1995-96), and Bangladesh's Mohammad Ashraful (2001-02). (If you click on the player profiles which are linked here, you can then find the scorecard from their Test debut.)

what's the significance of the number 626 on Kevin Pietersen's shirt? asked Jamie McAndrew from Bristol

It means that KP is the 626th man to represent England in a Test, dating from the very first match back in 1876-77. For a full list of the shirt numbers, click here. The Australians started the system: for a list of their numbers, click here. For the other teams, choose the name on the Countries dropdown on the main left-hand menu, and then click on "Players/Officials".

A question regarding the sweater that Geoff Boycott is wearing on his Cricinfo player page. I think the colours are black, red, yellow and black. As a kid, I used to think that it was an alternative to the plain white England sweater - but now I'm not so sure. Can you help? asked Paul Buckler from New Zealand

That is what used to be called the MCC touring sweater - it's what the England team wore in overseas Tests almost throughout the 20th century, starting soon after the Marylebone Cricket Club took on the responsibility for England's overseas tours in 1903-04. Even after that responsibility passed to the Test & County Cricket Board (now the ECB) around 1970 the England team was still known as MCC outside international matches on overseas tours until 1977-78, when it was considered confusing. Since then the team has been called an "England XI" when it is not playing Tests or ODIs. They continued to wear those colours - which are actually dark blue (not black), red and yellow - for a few more years until the "home" England sweater began to be used for overseas tours as well.

Which pair of openers have put on the most runs together in Tests and ODIs? asked Gordhan Valasai

The leaders in Tests are Gordon Greenidge and Desmond Haynes, who put on 6482 runs together in total for West Indies. They are well clear of the second-placed pair, Matthew Hayden and Justin Langer, whose tally stood at 4518 after the recent Lord's Test. Another current pairing, Marvan Atapattu and Sanath Jayasuriya of Sri Lanka, lie third with 4340. In ODIs the leading opening pair is Sourav Ganguly and Sachin Tendulkar, with 5621 for India, ahead of Greenidge and Haynes (5150), with Hayden and Adam Gilchrist a distant third with 3873, 20 more runs than Gilchrist added with Mark Waugh. Jayasuriya put on 3230 runs for Sri Lanka's first wicket in ODIs with Romesh Kaluwitharana, and 3191 to date with Atapattu.

Why do Test matches in England usually start on a Thursday? asked Prasanna from India

I think it's just a tradition - and an attempt to ensure that the match is boiling up nicely by the weekend, to maximise the crowd. In the days when there was no play on Sundays, it also meant that the rest day fell neatly about halfway through the match. Thursday starts became the norm in England shortly after the Second World War - before that matches often started on a Friday or Saturday, and between 1880 and 1912 often on Mondays. But since 1950, when the Lord's and Oval Tests began on a Saturday, only three Tests in England have not started on a Thursday: the Oval Tests of 1953 and 1955, and this year's second Test against Bangladesh at Chester-le-Street, which began on a Friday. In 1970 the first unofficial Test between England and the Rest of the World at Lord's started on a Wednesday, with a rest day for a general election the following day.