The influence of French on the English language wouldn't make any discernible difference between British and American syntax, considering that the French influence occurred centuries before there ever was an American version of English. British use of adjectives does not "mirror" that French. Some British people may choose to use that word order, but it is certainly not standard.
Syntax is the grammatical arrangement of words in a sentence. For the most part, there are no differences between American and British syntax. The biggest differences in the two versions of the language are in vocabulary, pronunciation, and spelling. However, there are some syntactical differences, such as these:
- In American English, collective nouns are considered to be singular: The audience was silent as she sang. In British English, collective nouns are plural: The audience were silent as she sang.
- The British use different prepositions in some expressions. Whereas Americans wait in line, the British wait on line. Americans stay in the hospital, but the British just stay in hospital.
- British English speakers like to say that they have got something, whereas Americans simply say have.
You can find many more examples in the book British or American English? A Handbook of Word and Grammar Patterns. Look for it in your local library or read portions of it on books.google.com.
With the tremendous influence of the French language upon English because of the Norman Conquest of 1066 in which William the Conqueror made French the official language and the language of the nobility, English yet retains remnants of the French grammatical arrangement of words. When the Americans began to develop their own language, they broke from many of the ways of pronunciation and spelling (e.g. they changed the -re ending of words such as theatre to theater) and of word order, but the British retained this order in some cases.
One example of this syntax is in the word order with adjectives which sometimes mirrors that of French. When, for instance, the famous English tennis championship is broadcast on television, the announcer says, "The Championship Wimbledon." Whereas American English would put the noun Wimbledon before the other noun Championship in order to change Wimbledon to an adjective, British English uses the French order of placing the adjective after the noun. This does not occur regularly, of course, but there are yet remnants of the French influence in England while the Americans did not retain them as they developed their own English.
Still another difference that is occurring more and more in American English is the use of the simple past for an action that has begun in the past but continues in the present. The English are more insistent upon the usage of the present perfect which is, of course, the appropriate tense.