Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Number | Serial No | Entered Service | Withdrawn | Kilometres Travelled |
| --- | --- | --- | --- | --- |
| 4101 | 1000 | 1 Dec 1953 | 6 Jun 1973 | 463,514 |
| 4102 | 1002 | 30 Oct 1953 | 30 Jun 1975 | 492,650 |
| 4103 | 1003 | 18 Jan 1954 | 2 Apr 1974 | 462,871 |
| 4104 | 1004 | 13 Jan 1954 | 12 Oct 1973 | 440,810 |
| 4105 | 1005 | 8 Feb 1954 | ? | ? |
| 4106 | 1006 | 21 Jan 1954 | 4 Aug 1972 | 406,288 |
| 4107 | 1007 | 25 Jan 1954 | 11 Aug 1973 | 446,167 |
| 4108 | 1008 | 22 Feb 1954 | 20 Dec 1967 | 402,026 |
| 4109 | 1009 | 11 Mar 1954 | 9 Feb 1972 | 426,074 |
| 4110 | 1010 | 10 Feb 1955 | 20 May 1974 | 476,489 |
Question:
which locomotive was the first to enter into service?
Answer:
4101